import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Main saphenous nerve runs in subcutaneous tissue 1-2cm medial to standard hamstring harvest incision on anteromedial proximal tibia. Infrapatellar branch emerges 8-10cm above joint line and travels inferolaterally, crossing the harvest incision site obliquely from superomedial to inferolateral direction. **Protection**: Identify nerve branches during superficial dissection in subcutaneous fat layer before incising sartorius fascia. Visualize branches and gently retract medially with vessel loop if encountered. Use blunt finger dissection technique rather than sharp dissection in superficial layers. Avoid electrocautery near nerve. If nerve injured or transected intra-operatively, must resect nerve end and bury proximally in muscle to prevent painful neuroma formation (neuroma causes chronic pain requiring reoperation in 5-10 percent of cases). **Location**: Located in popliteal fossa posterior to knee, running vertically posterior to tibial plateau and posterior knee capsule, deep to gastrocnemius and popliteus muscles. Positioned approximately 3-4cm posterior to posterior tibial cortex at level of joint line. Popliteal artery is medial to vein in upper fossa, lateral in lower fossa. **Protection**: Tibial tunnel positioning critical - ensure tibial tunnel aperture positioned 7mm anterior to posterior cortex (verify with lateral fluoroscopy and arthroscopic visualization of PCL). Use adjustable depth stop on tibial reamer set to prevent over-penetration through posterior cortex. During hamstring tendon stripping, keep tendon stripper pressed against posterior tibia (do not allow stripper to migrate posteriorly into popliteal fossa). If vascular injury suspected (sudden hemodynamic instability, massive posterior knee swelling, tense compartment), emergent vascular surgery consultation, possible angiography, surgical exploration and vascular repair required (catastrophic complication with amputation risk). **Location**: Wraps around fibular neck in posterolateral corner approximately 2-3cm distal to joint line. Travels superficial to lateral head of gastrocnemius muscle. Nerve lies posterior to lateral collateral ligament in posterolateral corner. Bifurcates into superficial and deep branches at fibular neck. **Protection**: During lateral meniscus repair with inside-out technique, make posterolateral safety incision and use retractor to protect nerve (nerve lies posterior to LCL and gastrocnemius). Palpate fibular neck to identify nerve course before any posterolateral incisions. All-inside meniscal repair devices significantly safer than inside-out for lateral meniscus (avoid nerve exposure entirely). If posterolateral portal needed for PCL or posterolateral corner work, use safe zone through popliteus interval. If nerve injury suspected post-operatively (foot drop, dorsiflexion weakness, loss of sensation on dorsum of foot), immediate EMG/NCS and neurology consultation - some injuries are neurapraxia (recover spontaneously), complete transection may need nerve exploration and grafting. **Location**: Posterior wall of femoral tunnel when drilling from anteromedial portal toward lateral femoral cortex. The posterior femoral cortex represents the thin bone shell (1-2mm thickness) between femoral tunnel and over-the-top position. Located at posterior-superior margin of lateral wall of intercondylar notch. **Protection**: Position femoral tunnel center 6-7mm anterior to over-the-top position (measured arthroscopically with depth gauge or ruler). Use hyperflexion (110-120 degrees) to improve visualization of posterior footprint. Select appropriate reamer depth and use gentle technique to avoid over-reaming. Check posterior wall integrity with probe after reaming (should feel solid bone, probe should not pass through posterior wall). If posterior wall blowout occurs (probe passes through), not catastrophic but requires adjustment - must use suspensory button fixation on lateral cortex (cannot use interference screw which relies on posterior wall integrity). Outcome equivalent if button fixation used appropriately. **Location**: Articular cartilage covering the weight-bearing surface of medial femoral condyle, extending to the superior margin of the femoral ACL footprint. The footprint lies 2-3mm inferior to the articular cartilage edge on the lateral wall of the intercondylar notch. **Protection**: Position femoral tunnel aperture 2-3mm inferior to articular cartilage margin to avoid creating chondral defect. Use arthroscopic visualization to identify cartilage edge before drilling guidewire. Avoid excessive notchplasty that removes supporting bone for articular cartilage. During burring for notchplasty, use high speed with light pressure and avoid plunging toward articular surfaces. If iatrogenic cartilage damage occurs (tunnel placed too proximal), creates focal chondral defect that may require secondary treatment (microfracture, osteochondral autograft, or cartilage restoration procedure) and increases risk of post-traumatic arthritis. ## ACL Injury Classification ### Acute versus Chronic - **Acute ACL injury**: Within 6 weeks of injury, significant effusion (hemarthrosis), pain, limited ROM, positive Lachman and pivot shift but may be difficult to perform due to guarding. MRI shows ACL discontinuity, high signal on T2 sequences, bone bruising (lateral femoral condyle and posterior lateral tibial plateau from pivot shift mechanism - hallmark finding). - **Chronic ACL injury**: Greater than 6 weeks from injury, effusion resolved, full ROM typically restored, compensatory muscle control developed, positive Lachman and pivot shift easier to elicit (no guarding). MRI shows absent ACL or poor quality remnant, resolution of bone bruising, possible secondary meniscal tears (20-30 percent develop delayed meniscal tears from chronic instability). ### Complete versus Partial Tears - **Complete ACL rupture**: Both anteromedial (AM) and posterolateral (PL) bundles torn. Clinical exam shows grade 3 Lachman (greater than 10mm anterior translation, no firm endpoint), grade 2-3 pivot shift (obvious clunk/reduction during test). MRI shows complete discontinuity of ACL, "empty notch" sign, PCL angle sign (PCL appears horizontal rather than oblique). Treatment: surgical reconstruction indicated for active patients with instability symptoms. - **Partial ACL tear**: One bundle intact (usually AM bundle torn with PL bundle intact, or vice versa). Clinical exam shows grade 1-2 Lachman (3-10mm translation with firm endpoint), grade 0-1 pivot shift (subtle or negative). MRI shows partial fiber continuity, intermediate signal intensity. Treatment controversial: can attempt conservative management with rehab and activity modification (50-70 percent succeed), surgical options include selective bundle reconstruction or completion to full reconstruction. ### Associated Injuries (O'Donoghue Unhappy Triad) - **ACL with medial meniscus and MCL tear**: Classic triad described by O'Donoghue, though lateral meniscus actually more common than medial in acute ACL injuries. Valgus and rotational mechanism. Treatment: ACL reconstruction with meniscal repair, MCL typically heals with conservative management (brace, protected weight-bearing) unless grade 3 complete tear. - **ACL with lateral meniscus tear**: More common than medial meniscus in acute ACL injuries (pivot shift mechanism traps lateral meniscus). Often peripheral longitudinal tear amenable to repair. Treatment: ACL reconstruction with meniscal repair dramatically improves healing (85-90 percent versus 60-70 percent isolated repair). - **Segond fracture**: Small avulsion fracture of lateral proximal tibia (lateral capsular ligament insertion), pathognomonic for ACL tear. Seen on AP X-ray as thin fleck of bone lateral to tibial plateau. May indicate associated anterolateral ligament (ALL) injury. Treatment: ACL reconstruction addresses instability, Segond fragment typically does not require fixation. ## Surgical Indications and Contraindications ### Absolute Indications - Complete ACL rupture with symptomatic instability (recurrent giving way episodes during activities of daily living or sport) that interferes with desired activity level - Failed conservative management (3-6 months of physiotherapy focusing on quadriceps and hamstring strengthening, proprioceptive training, activity modification) - Positive clinical examination (grade 2-3 Lachman test with soft endpoint, positive pivot shift grade 1-3) - Combined ACL tear with repairable meniscus tear (meniscal repair healing improved with concomitant ACL reconstruction providing stable knee environment) - Professional or high-level athletes requiring return to pivoting sports (soccer, basketball, football, skiing) - early reconstruction preserves menisci and prevents secondary injuries - Acute ACL injury in skeletally mature patient younger than 25 years in pivoting sport (high failure rate with conservative management in this population) ### Relative Indications - ACL tear in recreational athlete or active individual who wishes to continue pivoting activities - First-time patellar dislocation in contact athlete younger than 20 years (high incidence of associated ACL tear, should MRI to evaluate) - Combined ACL with other ligamentous injuries (PCL, posterolateral corner, MCL grade 3) - multiligament reconstruction - Revision ACL reconstruction for failed previous reconstruction with recurrent instability - Prophylactic reconstruction in high-risk occupation (military, police, firefighter) even if currently asymptomatic ### Contraindications - Significant knee arthritis (Kellgren-Lawrence grade 3-4 with joint space narrowing, osteophytes, subchondral sclerosis) - ACL reconstruction will not improve pain from arthritis, may worsen. Consider TKA instead. - Low-demand sedentary patient adapted to instability who has modified activities appropriately - conservative management reasonable - Medical comorbidities precluding surgery (severe cardiac disease, uncontrolled diabetes, active infection, coagulopathy not correctable) - Significant varus or valgus malalignment (greater than 5 degrees) - should correct alignment first with high tibial osteotomy (varus) or distal femoral osteotomy (valgus), then consider ACL reconstruction after alignment corrected - Active knee infection (absolute contraindication) - must treat infection first, delay reconstruction until infection resolved - Skeletal immaturity with wide-open growth plates (Tanner stage 1-2) - consider physeal-sparing techniques or delay until skeletal maturity (though newer evidence supports modified techniques in children) ### Patient Counseling Points - Natural history of ACL deficiency: 50-80 percent develop secondary meniscal tears over 5-10 years from chronic instability, 50-70 percent develop radiographic osteoarthritis by 15-20 years (even with reconstruction, though reconstruction delays onset) - Success rates: 90-95 percent achieve good-excellent outcomes with return to pre-injury activity level, 5-10 percent experience graft failure requiring revision - Return to sport timeline: 9-12 months minimum, though only 20-30 percent meet all objective criteria (strength, hop testing, psychological readiness) at 12 months - Risk of contralateral ACL tear: 10-15 percent within 2 years (higher in young athletes, female athletes) - emphasize bilateral injury prevention training - Alternatives: Conservative management with physiotherapy and activity modification (avoid pivoting sports) - success rate 30-50 percent in active individuals, higher in older sedentary patients **Examiner Question**: "A 35-year-old recreational skier has an ACL tear. What are the key factors that determine whether you recommend surgery or conservative management?" **Model Answer**: "The decision depends on three key factors: (1) **Functional instability** - recurrent giving way during activities of daily living or desired sports indicates need for surgery; (2) **Activity demands** - pivoting sports (skiing, soccer, basketball) require surgical stabilisation as conservative success rate is only 30-40% in active patients; and (3) **Associated injuries** - repairable meniscal tears strongly favor surgery as meniscal healing rates improve from 60% to 90% with concurrent ACL reconstruction. For this recreational skier, I would recommend surgery if they wish to continue skiing, as ACL deficiency makes pivoting sports extremely difficult and risks secondary meniscal injury." - **Avoid surgery in significant arthritis** (KL grade 3-4) - ACL reconstruction won't help and may worsen symptoms - **Active infection is absolute contraindication** - treat infection first - **Correct alignment before ACL** - if varus >5° do HTO first, if valgus >5° do DFO first - **Don't use allograft in young athletes** (<25yo) - 2-3x higher failure rate versus autograft - **Beware skeletal immaturity** - use physeal-sparing techniques in Tanner 1-2 ## ACL Functional Anatomy ### Osseous Attachments and Footprints - **Femoral footprint**: Located on lateral wall of intercondylar notch (medial aspect of lateral femoral condyle), oval-shaped area approximately 18mm (superior-inferior) by 11mm (anterior-posterior). Comprises 60 percent anteromedial (AM) bundle footprint (anterior and inferior portion) and 40 percent posterolateral (PL) bundle footprint (posterior and superior portion). Boundaries include: anterior - lateral intercondylar ridge (resident's ridge), posterior - over-the-top position, superior - articular cartilage margin (2-3mm distal to cartilage), inferior - roof of intercondylar notch. - **Tibial footprint**: Located on tibial plateau in following position - anterior to PCL tibial insertion (classic measurement 7mm anterior), posterior to anterior horn of lateral meniscus, medial to lateral tibial spine, centered at junction of anterior one-third and posterior two-thirds of tibia in AP dimension. Oval-shaped area approximately 17mm (mediolateral) by 11mm (anteroposterior). AM bundle inserts anteromedially, PL bundle inserts posterolaterally within footprint. ### Microscopic Structure and Blood Supply - **Collagen composition**: Type I collagen predominates (90 percent), type III collagen (10 percent). Parallel collagen fiber bundles oriented along long axis of ligament provide tensile strength. Crimp pattern (wavy appearance at rest) allows initial elongation without fiber loading - straightens under load before fibers actually stretch. - **Vascularity**: ACL is relatively avascular compared to other knee ligaments. Blood supply from middle genicular artery (branch of popliteal artery) which forms periligamentous plexus around ACL. Synovial covering provides nutrients via diffusion. Poor vascularity contributes to inability to heal after rupture (unlike MCL which has good blood supply and heals well conservatively). - **Innervation**: Mechanoreceptors (Ruffini endings, Pacinian corpuscles, Golgi tendon organs, free nerve endings) provide proprioceptive feedback. ACL contributes to joint position sense and neuromuscular control. Loss of proprioception after ACL rupture contributes to subjective instability and reinjury risk. ### Two-Bundle Concept - **Anteromedial (AM) bundle**: Larger bundle comprising 60 percent of ACL cross-sectional area. Inserts anteriorly and inferiorly on femur, anteromedially on tibia. Taut in flexion (90-120 degrees), relatively relaxed in extension. Primary restraint to anterior tibial translation, especially in flexion. Single-bundle ACL reconstruction typically targets AM bundle footprint center. - **Posterolateral (PL) bundle**: Smaller bundle comprising 40 percent of cross-sectional area. Inserts posteriorly and superiorly on femur, posterolaterally on tibia. Taut in extension (0-30 degrees), relaxed in flexion. Primary restraint to rotational loads and anterior translation near extension. Critical for rotational stability and negative pivot shift. - **Clinical relevance**: Double-bundle reconstruction (separate AM and PL tunnels and grafts) theoretically more anatomic, but Level 1 evidence shows no significant advantage over anatomic single-bundle reconstruction in outcomes or stability. Single-bundle targeting AM footprint center is standard. ## Biomechanical Function and Testing ### Primary and Secondary Restraints - **Primary restraint to anterior tibial translation**: ACL provides 85 percent of restraining force to anterior drawer at 30 degrees and 90 degrees flexion. Secondary restraints include: MCL (medial restraint, 5-10 percent), lateral capsule (lateral restraint, 5-10 percent), ITB (lateral, 3-5 percent). - **Rotational stability**: ACL provides primary restraint to internal rotation of tibia relative to femur, especially near extension (PL bundle). Critical for pivot shift phenomenon - ACL deficiency allows tibia to subluxate anteriorly and rotate internally in extension, then reduce with clunk as knee flexes (ITB transitions from extensor to flexor around 20-30 degrees flexion). - **Hyperextension restraint**: ACL becomes taut in hyperextension, limiting excessive extension beyond neutral. ACL-deficient knees may demonstrate increased hyperextension compared to contralateral (though many normal individuals have physiologic hyperextension). ### Clinical Examination Biomechanics - **Lachman test** (30 degrees flexion, anterior translation): Most sensitive test for ACL integrity (sensitivity 85-95 percent). Performed at 30 degrees where secondary restraints relaxed, isolating ACL function. Grade 0 equals firm endpoint with 1-2mm translation (normal), grade 1 equals firm endpoint with 3-5mm translation, grade 2 equals soft endpoint with 6-10mm translation, grade 3 equals no endpoint with greater than 10mm translation (complete ACL tear). - **Pivot shift test**: Most specific test for ACL tear (specificity 95-98 percent) and most predictive of functional instability. Simulates pivot shift injury mechanism. Starting in extension with internal rotation and valgus stress, tibia subluxates anteriorly (ACL-deficient knee cannot prevent this). As knee flexed to 20-30 degrees, ITB transitions from knee extensor to flexor creating force that reduces tibia back to anatomic position - this reduction creates palpable/visible clunk. Grade 0 equals negative (no shift), grade 1 equals glide (subtle shift felt but not seen), grade 2 equals clunk (obvious palpable and visible shift), grade 3 equals gross (dramatic shift with patient apprehension). - **Anterior drawer test** (90 degrees flexion): Less sensitive than Lachman (sensitivity 50-70 percent) as hamstrings can splint and secondary restraints tighter at 90 degrees. Foot stabilized in neutral rotation, pull tibia anteriorly. Graded similar to Lachman. ### Graft Biomechanics and Tunnel Position - **Native ACL strength**: Ultimate tensile strength approximately 2200N (range 1500-2500N), stiffness 240N/mm. Graft should approach these values for successful reconstruction. - **Isometry and graft tension**: Ideal tunnel position creates relatively isometric graft (similar length through ROM) to avoid over-constraint (graft too tight limiting ROM) or laxity (graft too loose causing instability). Anatomic tunnel position (AM bundle footprint center on femur and tibia) provides best isometry and most closely replicates native ACL function. Non-anatomic tunnel position (transtibial technique with anterior-vertical femoral tunnel) creates non-isometric graft with poor rotational stability. **Examiner Question**: "Explain the biomechanical basis of the pivot shift test and why it is the most important clinical test for ACL assessment." **Model Answer**: "The pivot shift test reproduces the functional instability mechanism of ACL deficiency: (1) **Starting position** - knee in extension with internal rotation and valgus stress. The ACL-deficient tibia subluxates anteriorly (cannot resist anterior translation at terminal extension); (2) **As knee flexes to 20-30°**, the ITB transitions from a knee extensor to a flexor, creating a posteriorly-directed force that reduces the subluxated tibia; (3) **The reduction clunk** is the tibia relocating from its subluxated position back to anatomic position. The test is most specific for ACL injury (95-98%) because it tests **rotational** instability - the PL bundle function near extension. This is why patients experience 'giving way' with cutting/pivoting activities where this mechanism occurs functionally." - **Lachman in acute injury** - may be limited by pain/guarding, examine under anaesthesia if uncertain - **False negative pivot shift** - posterior horn medial meniscus tear can block reduction - **Bilateral laxity** - always compare to contralateral limb, consider generalised ligamentous laxity - **Partial ACL tear** - may have positive Lachman (grade 1-2) but negative pivot shift (one bundle intact) - **Chronic ACL deficiency** - may have compensatory muscle control masking instability, still positive exam under anaesthesia ## Graft Choice Comparison ### BTB (Bone-Patellar Tendon-Bone) Autograft - **Advantages**: Fastest healing (bone-to-bone interface heals in 4 weeks versus tendon-to-bone 6-8 weeks), highest initial fixation strength with interference screws engaging bone plugs (greater than 1000N), gold standard for high-demand pivoting athletes, proven long-term outcomes (20 plus years follow-up), best graft if revision ACL needed in future (preserved hamstrings for revision) - **Disadvantages**: Higher donor site morbidity - anterior knee pain (15-30 percent versus 5-10 percent hamstring), kneeling pain (20-40 percent), patellar tendinitis (5-10 percent), patellofemoral pain and crepitus (10-20 percent), patellar fracture risk (less than 1 percent but catastrophic), quadriceps tendon rupture risk (less than 1 percent), larger more visible scar, preserved bone stock for revision but patellar tendon not available - **Best for**: High-level athletes in pivoting sports requiring fastest healing and return to sport, patients with previous hamstring harvest, patients with generalized ligamentous laxity (BTB stiffer graft) ### Hamstring Autograft (Quadrupled Gracilis-Semitendinosus) - **Advantages**: Lower donor site morbidity - anterior knee pain (5-10 percent), less kneeling pain, smaller incision with better cosmesis, no patellar fracture risk, preserved extensor mechanism, good graft for primary ACL in most patients, can harvest contralateral for revision if needed - **Disadvantages**: Slower tendon-to-bone healing (6-8 weeks), potential hamstring weakness (10-20 percent peak torque deficit though usually compensated by biceps femoris), higher tunnel widening rates (20-30 percent radiographically though clinically insignificant in most), requires adequate graft length (greater than 24cm combined) and diameter (greater than 8mm preferred), saphenous nerve injury risk (numbness 10-20 percent), cannot use if previous hamstring harvest - **Best for**: Most primary ACL reconstructions in active patients, females with concern about anterior knee pain cosmesis, patients concerned about donor site morbidity, recreational athletes ### Quadriceps Tendon Autograft - **Advantages**: Increasingly popular option, thicker graft (9-10mm typical), bone plug on patellar end (can use interference screw femoral fixation for bone-to-bone healing), larger cross-sectional area, good option if previous hamstring harvest, intermediate donor site morbidity between BTB and hamstring, minimal harvest site pain at 2 years, can harvest long graft (useful for revision or multiligament reconstruction) - **Disadvantages**: Limited long-term outcome data compared to BTB and hamstring (though short-term outcomes excellent), potential extensor mechanism disruption, harvest technically more demanding, quadriceps tendon rupture risk (less than 1 percent) - **Best for**: Large patients requiring thick graft, previous hamstring harvest, revision ACL reconstruction, multiligament reconstruction, older patients (greater than 40 years) ### Allograft (Cadaveric Tissue) - **Advantages**: No donor site morbidity (major advantage), unlimited graft availability for multiligament reconstruction, shorter operative time (no harvest), useful in revision surgery to avoid additional donor site, options include BTB, Achilles tendon, tibialis anterior, hamstring - **Disadvantages**: Slower incorporation and remodeling (graft revascularization takes 6-12 months versus 3-6 months autograft), higher failure rate in young active patients younger than 25 years (2-3x higher versus autograft in multiple studies), disease transmission risk minimal but non-zero (HIV 1 in 1.6 million with modern screening and processing, hepatitis similar), higher cost, inferior outcomes in pivoting athletes, processing methods (gamma irradiation, chemical sterilization) may weaken graft - **Best for**: Older lower-demand patients (greater than 40 years, recreational activities only), multiligament reconstruction (to minimize donor site morbidity), revision ACL reconstruction (to preserve autograft sources), patients who refuse autograft harvest ## Femoral Tunnel Techniques ### Transtibial Technique (Historical) - **Technique**: Single tibial tunnel drilled first, femoral tunnel drilled through tibial tunnel using transtibial guide. Single-pass drilling of both tunnels. - **Advantages**: Technically easier, shorter learning curve, less operative time, good visualization during drilling - **Disadvantages**: Geometric constraints force femoral tunnel anterior and vertical (11-12 o'clock position on right knee), non-anatomic position, poor rotational stability (PL bundle not reconstructed), higher failure rates in pivoting sports, positive residual pivot shift in 20-30 percent. Largely abandoned by most surgeons. - **Historical note**: Was standard technique 1980s-early 2000s until biomechanical studies and clinical outcomes demonstrated superiority of anatomic AM portal technique ### Anteromedial Portal Technique (Current Gold Standard) - **Technique**: Femoral tunnel drilled independently through anteromedial portal after tibial tunnel created. Requires hyperflexion (110-120 degrees) for access to posterior footprint. Uses offset guide or flexible reaming system. Can achieve anatomic 10-11 o'clock position (right knee). - **Advantages**: True anatomic tunnel position replicating native ACL AM bundle footprint, oblique graft orientation, superior rotational stability (better restraint to pivot shift), lower failure rates, better patient-reported outcomes, restoration of near-normal knee kinematics. Level 1 evidence supports superiority over transtibial technique. - **Disadvantages**: Technically more demanding, steeper learning curve, requires good arthroscopic skills, hyperflexion may be difficult in stiff knee or obese patient, risk of posterior wall blowout if tunnel placed too posterior, slightly longer operative time - **Tips for success**: Use hyperflexion (110-120 degrees) or figure-4 position, identify anatomic landmarks (resident's ridge, over-the-top, cartilage margin), position tunnel 6-7mm anterior to over-the-top, confirm guidewire position before reaming ### Outside-In Technique - **Technique**: Femoral tunnel drilled from outside (lateral femoral cortex) toward inside (intercondylar notch). Separate incision over lateral femoral condyle. Guidewire placed at anatomic footprint under arthroscopic visualization, drilled from inside out, reamed from outside in. - **Advantages**: Can achieve anatomic tunnel position, good control of femoral tunnel position, may be easier in revision cases with previous tunnel, avoids hyperflexion requirement - **Disadvantages**: Requires additional lateral thigh incision (cosmesis, morbidity), risk of injury to vastus lateralis muscle or lateral structures, more difficult to achieve true posterolateral position compared to AM portal, longer operative time, less commonly used - **Indications**: Primarily used in revision ACL when AM portal access difficult due to previous tunnel or hardware, or in cases where hyperflexion not achievable ## Fixation Method Variations ### Femoral Fixation Options - **Suspensory cortical button** (Endobutton, TightRope, RetroButton): Current gold standard for hamstring grafts. Highest biomechanical strength (1000-1200N), relies on cortical bone of lateral femoral cortex (strongest bone), adjustable graft tensioning before locking, no intra-articular hardware, easy revision. Requires button flip confirmation. Complications: button malposition if fails to flip (1-2 percent), suture breakage rare with modern devices, requires intact lateral cortex. - **Interference screw** (bioabsorbable or metal): Historic standard, still excellent for BTB bone plugs. Biomechanical strength for hamstring lower (500-700N relying on cancellous bone versus 1000 plus N for BTB bone-to-bone). Risk of graft laceration with divergent screw placement (2-5 percent), screw prominence causing irritation (1-2 percent). Bioabsorbable screws avoid MRI artifact but risk of inflammatory reaction (foreign body synovitis 1-3 percent), screw breakage, tunnel widening. Metal screws stronger but MRI artifact, permanent implant. - **Cross-pins** (TransFix, RigidFix): Drill transverse pin through femoral tunnel and graft, provides rotational stability to graft. Biomechanical strength high (600-900N). Technically demanding, requires specific instrumentation, risk of pin malposition or graft laceration, more difficult revision if needed. Less commonly used now. - **Hybrid fixation**: Combination of suspensory button plus interference screw for maximum security. Some surgeons use in high-demand athletes or revision cases. Adds operative time and cost. No evidence of improved outcomes versus button alone in primary ACL. ### Tibial Fixation Options - **Interference screw**: Gold standard for tibial fixation for both hamstring and BTB. Screw diameter 1mm larger than tunnel (9mm screw for 8mm tunnel), length 25-30mm, parallel to graft (or slight divergence less than 15 degrees). Biomechanical strength 500-700N for hamstring (adequate as graft itself weaker link), greater than 1000N for BTB. Complications: screw divergence lacerating graft (1-2 percent), inadequate purchase in poor bone quality (elderly, osteoporotic). - **Post and screw with washer**: Backup fixation or primary fixation in poor bone quality. Graft sutures tied over post or bone bridge on anterior tibia, secured with screw and spiked washer. Distributes load over wider area. Biomechanical strength 400-600N adequate for backup. Position 2-3cm distal to tibial tunnel aperture. Complications: suture breakage (rare), washer irritation requiring removal (2-3 percent). - **Staples**: Historic method, less commonly used now. Drive staple over graft on anterior tibia. Risk of soft tissue irritation (5-10 percent), staple migration, inferior biomechanical strength (300-500N). May damage graft during insertion. **Examiner Question**: "A 22-year-old elite netball player requires ACL reconstruction. What graft would you recommend and what femoral tunnel technique would you use?" **Model Answer**: "For this high-demand young female athlete, I would recommend **BTB autograft** with **anatomic AM portal femoral tunnel technique**: (1) **BTB rationale** - fastest bone-to-bone healing (4 weeks vs 6-8 weeks hamstring), highest fixation strength (>1000N), lowest re-rupture rate in pivoting athletes, and preserves hamstrings for potential future revision; (2) **AM portal technique rationale** - Level 1 evidence shows superior rotational stability versus transtibial (94% vs 78% negative pivot shift, Forsythe AJSM 2010), better IKDC scores (91 vs 83), and higher return to sport (87% vs 74%). The anatomic oblique graft orientation restores rotational stability critical for cutting sports. I would counsel her regarding anterior knee pain (15-30%) and kneeling pain (20-40%) with BTB but emphasise the biomechanical advantages for elite sport." - **Transtibial technique largely abandoned** - forced non-anatomic vertical tunnel (11-12 o'clock), poor rotational stability, 20-30% residual pivot shift - **AM portal requires hyperflexion 110-120°** - may be difficult in obese or stiff knee patients - **Suspensory button MUST flip** - confirm with fluoroscopy or by feel, incomplete flip = loss of fixation - **Hamstring graft diameter <8mm** - significantly higher failure rate, consider BTB or quadriceps if small tendons - **Interference screw risk with hamstring** - divergent screw lacerates graft (2-5%), use parallel technique ## Landmark Studies and Meta-Analyses ### Graft Choice Evidence - **Mohtadi et al. JBJS 2011**: Level 1 RCT comparing BTB versus hamstring autograft, 330 patients, 2-year follow-up. Results: No significant difference in IKDC scores, Lysholm scores, activity level, or graft failure rates (4.9 percent BTB versus 4.2 percent hamstring). BTB group had higher kneeling pain (46 percent versus 19 percent) and anterior knee pain. Hamstring group had higher tunnel widening (radiographic). Conclusion: Equivalent clinical outcomes, choose based on patient factors and surgeon preference. - **Xie et al. Arthroscopy 2015 Meta-analysis**: 19 RCTs, 2,332 patients, BTB versus hamstring. Results: No difference in knee stability (Lachman, pivot shift, KT-1000), IKDC scores, Lysholm scores, or graft failure rates at minimum 5-year follow-up. BTB had higher kneeling pain, anterior knee pain, and extension loss. Hamstring had higher flexion deficit and tunnel widening. Conclusion: Both grafts provide excellent long-term stability and outcomes. - **Samuelsen et al. AJSM 2017**: Systematic review of allograft versus autograft in patients younger than 25 years. Results: Allograft had 2-3x higher failure rate (18 percent versus 7 percent) in young active patients. Worse functional outcomes and return to sport. Conclusion: Autograft superior in young active patients, allograft should be avoided in this population. ### Tunnel Position and Technique - **Yagi et al. Arthroscopy 2002**: Biomechanical study comparing transtibial versus AM portal femoral tunnel position. Results: Transtibial technique produced anterior femoral tunnel (11-12 o'clock), AM portal achieved anatomic posterolateral position (10 o'clock). Anatomic position provided better rotational stability and more closely replicated native ACL kinematics. Conclusion: AM portal technique biomechanically superior. - **Forsythe et al. AJSM 2010**: Clinical study comparing transtibial versus AM portal technique, 200 patients, 2-year follow-up. Results: AM portal group had better rotational stability (negative pivot shift 94 percent versus 78 percent), higher IKDC scores (91 versus 83), better return to sport (87 percent versus 74 percent). Conclusion: AM portal technique superior clinical outcomes versus transtibial. - **Bernard et al. Arthroscopy 1997**: Described quadrant method for assessing femoral tunnel position on lateral radiograph. Divide femoral footprint into 25 percent segments (quadrants) in both AP and height dimensions. Ideal tunnel center at 26 percent from anterior border, 29 percent from superior border (AM bundle center). Now standard method for tunnel position assessment. ### Fixation Methods - **Eguchi et al. AJSM 2016**: Biomechanical comparison of femoral fixation devices for hamstring grafts. Results: Cortical button (Endobutton) highest strength (1127N), followed by TransFix cross-pin (823N), interference screw (654N). All exceeded expected physiologic loads during rehab (less than 500N). Conclusion: Suspensory button provides strongest femoral fixation for hamstring. - **Kousa et al. AJSM 2003**: Clinical comparison of femoral interference screw versus Endobutton for hamstring ACL, RCT 60 patients, 2-year follow-up. Results: No difference in clinical outcomes (IKDC, Lachman, KT-1000). Endobutton group had more tunnel widening but clinically insignificant. Conclusion: Both methods effective, tunnel widening with button does not affect outcomes. ### Meniscal Repair with ACL - **Shelbourne et al. Arthroscopy 2000**: Prospective study of meniscal repair with ACL reconstruction versus isolated meniscal repair. Results: Meniscal repair with concurrent ACL had 90 percent healing rate versus 50-60 percent isolated repair at 5-year follow-up. Mechanism: ACL provides stable environment and hemarthrosis provides healing factors. Conclusion: Concomitant ACL dramatically improves meniscal repair healing. - **Pujol et al. Orthop Traumatol Surg Res 2015**: Systematic review of meniscal repair outcomes. Results: Healing rates - red-red zone 85-90 percent, red-white zone 75-80 percent, white-white zone 10-20 percent (should not repair). Vertical longitudinal tears heal best (85 percent), radial tears worst (50 percent). Conclusion: Location and pattern predict healing success. ### Rehabilitation and Return to Sport - **Barber-Westin and Noyes AJSM 2011**: Analysis of accelerated versus non-accelerated rehab after ACL reconstruction. Results: No difference in graft failure, stability, or outcomes between immediate motion versus delayed motion protocols. Early motion group returned to activities faster. Conclusion: Early motion safe and beneficial versus prolonged immobilization. - **Grindem et al. BJSM 2016**: Systematic review of return to sport criteria and outcomes. Results: Only 55 percent of ACL reconstruction patients return to pre-injury sport level. Patients returning before 9 months had higher re-rupture rate (20 percent) versus after 9 months (7 percent). Strength testing critical - less than 90 percent LSI associated with higher re-injury risk. Conclusion: Delay return to sport until 9-12 months and meet objective criteria (strength, hop tests, psychological readiness). ### Long-Term Outcomes and Osteoarthritis - **Oiestad et al. BJSM 2009 Meta-analysis**: Long-term follow-up (10-20 years) after ACL reconstruction. Results: 50-70 percent develop radiographic osteoarthritis regardless of treatment (reconstruction versus conservative). Meniscectomy strongest predictor of arthritis (80-90 percent if total meniscectomy). ACL reconstruction may delay onset but does not prevent arthritis. Conclusion: ACL injury is start of joint degeneration cascade, focus on meniscal preservation critical. **Examiner Question**: "What does the evidence tell us about the key modifiable factors that affect outcomes and long-term prognosis after ACL reconstruction?" **Model Answer**: "The evidence highlights several modifiable factors: (1) **Meniscal preservation is critical** - Oiestad meta-analysis shows 80-90% develop arthritis after meniscectomy versus 50-70% with intact meniscus; Shelbourne data shows meniscal repair healing improves from 60% to 90% with concurrent ACL reconstruction; (2) **Tunnel position determines stability** - Forsythe AJSM 2010 shows AM portal anatomic technique achieves 94% negative pivot shift versus 78% with transtibial; (3) **Return to sport timing** - Grindem BJSM 2016 shows return before 9 months has 20% re-rupture versus 7% after 9 months; (4) **Graft choice in young athletes** - Samuelsen AJSM 2017 shows allograft has 2-3x higher failure rate in patients under 25 years. These are the factors we can control to optimise outcomes." - **ALWAYS repair meniscus if possible** - meniscectomy is the strongest predictor of arthritis, repair healing rate 90% with concurrent ACL - **Delay return to sport until 9-12 months** - earlier return = 2-3x higher re-rupture rate - **Avoid allograft in young athletes (<25yo)** - Level 1 evidence shows 2-3x higher failure rate - **Use AM portal technique** - Level 1 evidence shows superior rotational stability versus transtibial - **Meet objective criteria before return** - LSI >90%, hop tests >90%, ACL-RSI >56 ## Expected Outcomes ### Return to Sport - **Timeline**: Minimum 9-12 months before return to unrestricted pivoting sports (soccer, basketball, football, skiing). Earlier return (6-9 months) associated with 2-3x higher re-rupture rate. Only 20-30 percent of patients meet ALL objective criteria at 12 months (greater than 90 percent strength LSI, hop tests greater than 90 percent, psychological readiness ACL-RSI score greater than 56). Continue training until criteria met even if requires 15-18 months. - **Return to sport rates**: 55-65 percent return to pre-injury sport level (competitive or recreational), 80-90 percent return to some sport (may be lower level or different sport), 10-20 percent never return to sport (fear, re-injury, loss of confidence, career change). Higher return rates in professional athletes (70-80 percent due to motivation, resources, compliance) versus recreational (50-60 percent). - **Performance after return**: Most studies show decreased performance metrics (vertical jump, sprint times, agility tests) at 1-2 years post-reconstruction compared to pre-injury baseline. Gradual improvement to 2-3 years. Some athletes never regain pre-injury level especially power and explosive movements. ### Stability and Function - **Clinical stability**: 90-95 percent achieve negative Lachman (grade 0-1 with firm endpoint less than 3mm) and negative pivot shift (grade 0) at 2-year follow-up with anatomic tunnel technique. 5-10 percent have grade 1-2 Lachman (mild laxity) but may be asymptomatic. 2-5 percent have positive pivot shift (indicates functional failure requiring revision consideration). - **Instrumented laxity** (KT-1000 arthrometer): Mean side-to-side difference 1-2mm (excellent less than 3mm, good 3-5mm, fair 5-7mm, poor greater than 7mm). 85-90 percent achieve less than 3mm difference. Tunnel widening does not correlate with increased laxity in most studies. - **Patient-reported outcomes**: Mean IKDC subjective score 85-90 (out of 100), Lysholm score 90-95, Tegner activity score returns to within 1-2 levels of pre-injury (pre-injury mean 7-8, post-op mean 6-7). Satisfaction rates 85-90 percent at 2-5 years. ### Graft Healing and Maturation - **Tunnel healing**: Hamstring tendon-to-bone healing takes 6-8 weeks (Sharpey fiber formation at tunnel interface), BTB bone-to-bone healing 4 weeks (faster). Graft incorporation continues to 12-24 months (collagen remodeling, revascularization, innervation). - **Graft maturation phases**: Necrosis phase (0-4 weeks) - graft relatively avascular, dependent on synovial fluid diffusion, weakest point in rehab. Revascularization phase (4-12 weeks) - new blood vessel ingrowth from synovium and bone tunnels, cellular infiltration. Remodeling phase (3-12 months) - collagen reorganization along lines of stress (Wolff's law), graft gains strength. Maturation phase (12-24 months) - continued collagen remodeling, graft approaches but never fully reaches native ACL strength. - **Biomechanical properties**: Graft ultimate tensile strength at 12 months approximately 50-70 percent of native ACL (animal studies), continues to improve to 24 months (70-80 percent). Never fully reaches native strength. Stiffness similarly reduced. ### Tunnel Widening - **Incidence**: Radiographic tunnel widening (greater than 1-2mm diameter increase) in 20-30 percent on X-ray or MRI. More common with hamstring (30 percent) versus BTB (10 percent), suspensory fixation (35 percent) versus interference screw (20 percent), femoral tunnel (25 percent) versus tibial tunnel (20 percent). - **Clinical significance**: Most tunnel widening asymptomatic and clinically insignificant. Does not correlate with increased laxity (KT-1000), worse outcomes (IKDC, Lysholm), or higher graft failure rates in majority of studies. Main concern for future revision surgery (widened tunnels complicate tunnel placement, may require bone grafting and two-stage approach). - **Mechanism**: Biological factors (synovial fluid entry into tunnel via tendon-graft interface causing osteolysis, inflammatory response, biological remodeling) and mechanical factors (micro-motion of graft "windshield wiper effect", stress-shielding of bone). Most widening occurs first 6-12 months then stabilizes. ## Common Complications - Detailed Management ### Graft Failure and Re-rupture (5-10 percent) - **Risk factors**: Young age (less than 20 years: 15-20 percent failure rate), female gender (2x higher than males), premature return to sport (before 9 months or before meeting objective criteria), non-anatomic tunnel position (anterior femoral tunnel from transtibial technique), generalized ligamentous laxity, genetics (family history of ACL injury), high-risk sports (soccer, basketball, football), contralateral ACL injury (indicates risk phenotype). - **Diagnosis**: Clinical exam (recurrent instability, positive pivot shift, positive Lachman), MRI (graft discontinuity or non-visualization on T1 and T2 sequences, increased signal within graft suggesting partial tear or synovitis, can assess tunnel position and associated injuries). CT 3D reconstruction (gold standard for tunnel position assessment using Bernard quadrant method). - **Management decision-making**: Conservative management if low-demand patient adapted to instability, older patient, significant arthritis present (activity modification, quad strengthening, possible hinged brace for sports). Surgical revision ACL if symptomatic instability in active patient desiring return to sport. Pre-operative assessment critical before revision: (1) Identify cause of failure (tunnel malposition 50-60 percent of failures, new traumatic injury 20-30 percent, biological failure/poor incorporation 10-20 percent), (2) Assess tunnel position on CT 3D (if greater than 5mm off anatomic requires two-stage revision), (3) Assess tunnel widening (if greater than 15mm requires bone grafting), (4) Assess alignment (varus/valgus greater than 5 degrees requires corrective osteotomy first), (5) Assess meniscal status (meniscal deficiency may need allograft transplant), (6) Assess cartilage (Outerbridge grade 3-4 changes may preclude revision or require cartilage restoration). - **Revision technique**: Two-stage revision if significant tunnel malposition or widening - Stage 1: remove graft, bone graft tunnels with cancellous autograft from iliac crest or structural allograft, compress and pack tightly, allow 3-6 months for incorporation confirmed on CT; Stage 2: drill new anatomic tunnels (can overlap old tunnels if bone incorporated), new graft reconstruction. Single-stage revision if tunnels in acceptable position and normal size - remove old graft, drill new tunnels (can drill through old tunnels if close to correct position), new graft. Graft choice for revision: allograft common to avoid additional donor site morbidity (though autograft options include contralateral hamstring, ipsilateral quadriceps tendon if not previously used, BTB if hamstring used primarily). Revision outcomes: inferior to primary (70-80 percent good-excellent versus 90-95 percent primary), higher re-failure rate (10-15 percent versus 5-10 percent), lower return to sport (50-60 percent versus 65-75 percent). ### Stiffness and Arthrofibrosis (Mild 5-10 percent, Severe 1-2 percent) - **Causes of extension loss**: Graft impingement (tibial tunnel too anterior most common cause, accounts for 50-70 percent), cyclops lesion (fibrous nodule from ACL remnant 10-15 percent), graft over-constraint (too tight 10 percent), inadequate rehabilitation (prolonged immobilization), infection (septic arthritis causes severe arthrofibrosis), hemarthrosis (large blood clot), genetic predisposition. - **Causes of flexion loss**: Graft over-constraint (graft too tight limiting flexion), patella baja (patella sits low from scarring of infrapatellar fat pad and patellar tendon), suprapatellar pouch scarring (adhesions preventing proximal patellar excursion), prolonged immobilization (capsular contracture), infrapatellar contracture syndrome (severe scarring of anterior knee structures). - **Prevention strategies**: Achieve full extension (0 degrees) before leaving OR at index surgery (non-negotiable checkpoint), early motion protocol post-operatively (start ROM day 1, not delayed), avoid prolonged immobilization (no locked bracing beyond 1-2 weeks), aggressive extension exercises from day 1 (prone hangs for 10-15 minutes three times daily, heel prop extension, wall slides), control swelling (ice, compression, elevation), early physiotherapy referral (within first week). Avoid surgery during acute inflammatory phase (less than 2 weeks post-injury with significant swelling) - delay to 3-6 weeks for inflammation to settle. - **Treatment algorithm by severity and timing**: Mild loss (less than 5 degrees extension, less than 10 degrees flexion) - aggressive physiotherapy for 4-6 weeks (prone hangs, patellar mobilization, extension splinting at night, NSAIDs though some concern about bone healing so consider delaying until 6 weeks post-op), continue until improved. Moderate loss or failed PT (5-10 degrees extension) - manipulation under anesthesia (MUA) if less than 12 weeks post-op while tissue still amenable (gently force knee into extension and flexion under anesthesia to break adhesions), success rate 70-80 percent if done early, may need serial manipulations weekly for 2-3 sessions, some surgeons combine with arthroscopic lysis of adhesions. Severe loss or chronic greater than 3-6 months or failed MUA - arthroscopic lysis of adhesions (remove scar tissue from suprapatellar pouch, debride intercondylar notch, excise cyclops lesion if present, release infrapatellar fat pad contracture, notchplasty if impingement, possible tibial tubercle anteriorization for patella baja), outcomes variable (50-70 percent achieve functional ROM), some patients develop recurrent scarring requiring multiple procedures. Post-lysis rehabilitation: immediate aggressive ROM exercises (continuous passive motion machine, aggressive PT twice daily), extension splinting at night, NSAIDs, possibly manipulation under anesthesia at 7-10 days post-lysis to maintain ROM. ### Infection - Septic Arthritis (Less than 1 percent) - **Causative organisms**: Staphylococcus aureus 60-70 percent most common (including MRSA 20-30 percent of S. aureus), Staphylococcus epidermidis 15-20 percent (indolent course, biofilm formation on graft and hardware), Gram-negative organisms 5-10 percent (E. coli, Pseudomonas), Streptococcus species 3-5 percent. Rarely fungal or mycobacterial in immunocompromised patients. - **Diagnosis and work-up**: High index of suspicion for any patient with excessive pain and swelling post-operatively. Joint aspiration (urgent, ideally before antibiotics) - send for: (1) Cell count with differential (WBC greater than 50,000 with greater than 90 percent PMNs highly suggestive of infection, WBC greater than 3,000 concerning, though post-operative values overlap), (2) Gram stain (positive in only 30-40 percent but if positive highly specific), (3) Aerobic and anaerobic culture with sensitivity (hold cultures 5-7 days, may need extended culture for slow-growing organisms like S. epidermidis), (4) Synovial fluid CRP (newer test, greater than 10mg/L highly specific for infection). Blood tests: WBC (elevated but non-specific), ESR (elevated greater than 40 suggestive), CRP (elevated greater than 50mg/L highly suggestive, trends useful for monitoring treatment response). Imaging: X-ray usually normal acutely (later shows joint space widening, periarticular osteopenia), MRI shows large effusion, synovial enhancement with contrast, periarticular soft tissue edema. - **Treatment algorithm by timing**: Acute/early infection (less than 4 weeks post-op, acute presentation) - arthroscopic irrigation and debridement (I and D) urgently within 24-48 hours of diagnosis (remove infected fluid and tissue, debride synovium, copious irrigation with 9-12 liters normal saline or dilute betadine solution, polyexchange technique using multiple inflow/outflow cycles to clear bacteria). Graft retention if caught early (infection less than 2-4 weeks, graft appears viable on arthroscopy, no loosening, fixation intact). Start empiric IV antibiotics immediately after cultures obtained: vancomycin 15mg/kg every 12 hours (covers MRSA and streptococcus) plus third-generation cephalosporin ceftriaxone 2g daily (covers gram-negatives), then narrow spectrum based on culture and sensitivity results. Continue IV antibiotics 2-6 weeks depending on organism and response (infectious disease consultation for duration guidance). May require repeat I and D in 24-48 hours if not improving clinically (persistent fever, worsening effusion, elevated inflammatory markers). Late infection (greater than 4 weeks post-op) or failed early treatment - higher graft contamination, often requires graft removal (explant ACL graft and all fixation hardware), thorough arthroscopic or open debridement (remove all infected tissue, may need synovectomy), IV antibiotics for 6 weeks (infectious disease-directed based on cultures and sensitivities), then staged reconstruction once infection cleared (wait 6-12 months, confirm normal inflammatory markers ESR less than 20 and CRP less than 10, negative joint aspiration culture before revision ACL). Outcomes: early treatment with graft retention - most patients retain graft with good outcomes (though increased stiffness risk 20-30 percent requiring aggressive PT or manipulation). Delayed treatment or late infection - usually requires graft removal with poor outcomes (chronic pain, stiffness, possible chronic low-grade infection despite treatment, revision ACL after infection clearance has inferior outcomes to routine revision). ### Cyclops Lesion (2-5 percent) - **Pathophysiology**: Focal fibrous nodule forming anterior to ACL graft in intercondylar notch. Mechanism: residual ACL stump tissue left anteriorly undergoes fibrous proliferation from repeated impingement on roof of intercondylar notch (anterior femur) during terminal extension. Alternatively, anterior graft impingement can stimulate fibrous reaction forming nodule. More common with remnant-preserving technique (intentional preservation of ACL tibial stump) or inadequate ACL stump debridement at index surgery. Named "cyclops" because arthroscopic appearance resembles eye of cyclops. - **Presentation and diagnosis**: Extension loss (most common presentation) - mechanical block preventing terminal extension, typically 5-15 degree flexion contracture (range 3-20 degrees). Clicking or clunking sensation in knee during terminal extension (as lesion catches on roof of intercondylar notch). Anterior knee pain (from impingement). Timing: symptoms typically develop 6 weeks to 6 months post-operatively (time for fibrous proliferation to occur). Physical exam: firm mechanical block to terminal extension (versus soft block from effusion or pain/muscle guarding). MRI: soft tissue nodule anterior to ACL graft located in anterior intercondylar notch between graft and anterior femur, T1 low signal intensity, T2 low to intermediate signal intensity (fibrous tissue), enhances with gadolinium contrast administration. - **Prevention**: Adequate ACL stump debridement at index surgery (remove stump from anterior aspect of intercondylar notch where it can impinge on roof during extension, use motorized shaver and radiofrequency ablation device), notchplasty if narrow notch or impingement risk identified (remove bone from lateral wall of notch to prevent impingement), ensure graft does not impinge on roof during final ROM check before closing (visualize arthroscopically through full ROM, if impingement noted must address with notchplasty before leaving OR). - **Treatment**: Arthroscopic excision of cyclops lesion (definitive treatment with excellent outcomes). Technique: arthroscopy through standard AL and AM portals (same as index surgery), identify lesion (white/cream colored fibrous nodule anterior to graft, typically 5-15mm diameter), use motorized shaver to excise lesion (remove completely - partial excision may lead to recurrence), can use radiofrequency ablation device to shrink and remove tissue, may need to perform notchplasty if roof impingement contributed to lesion formation (remove bone from lateral wall of notch), check final ROM (should restore terminal extension immediately after lesion removed - if extension still limited suggests other pathology such as general arthrofibrosis). Post-excision rehabilitation: aggressive extension exercises immediately (prone hangs, extension splinting at night) to maintain extension and prevent recurrence, ROM exercises to regain flexion if also limited. Outcomes: excellent - most patients achieve full extension (0 degrees) immediately after excision with mechanical block removed, recurrence rare (less than 5 percent) if complete excision performed. Delay in diagnosis and treatment can lead to permanent flexion contracture from soft tissue adaptive shortening (posterior capsule contracture, hamstring contracture) and patellofemoral arthritis from chronic quadriceps shutdown (inability to fully activate quadriceps if knee not fully extended), so early recognition and treatment important to prevent long-term sequelae. **Examiner Question**: "Your patient develops increasing pain and swelling 3 weeks after ACL reconstruction with fever. How do you manage this?" **Model Answer**: "I would suspect septic arthritis and manage urgently: (1) **Immediate work-up** - joint aspiration under sterile conditions BEFORE starting antibiotics, send for cell count (WCC >50,000 with >90% PMNs), Gram stain, culture and sensitivity (aerobic/anaerobic, hold 5-7 days), blood for WCC, ESR, CRP; (2) **Empiric antibiotics** - start immediately after cultures obtained with vancomycin 15mg/kg q12h (covers MRSA) plus ceftriaxone 2g daily (covers gram-negatives); (3) **Urgent arthroscopic I&D** - within 24-48 hours, copious irrigation 9-12L, polyexchange technique, debride synovium, GRAFT RETENTION if infection <4 weeks and graft viable; (4) **Post-op management** - IV antibiotics 2-6 weeks guided by cultures and infectious disease input, repeat I&D in 48 hours if not improving. Early treatment with graft retention has good outcomes; delayed treatment usually requires graft explant and staged revision." - **Arthrofibrosis prevention is key** - full extension 0° before leaving OR is NON-NEGOTIABLE checkpoint, early motion from day 1 - **Graft failure pattern recognition** - traumatic re-rupture from inadequate healing (<6 months), atraumatic failure suggests tunnel malposition - **Cyclops lesion** - mechanical block to terminal extension 6 weeks-6 months post-op, treat with arthroscopic excision - **Septic arthritis** - aspirate BEFORE antibiotics, urgent I&D within 24-48 hours, graft retention if <4 weeks - **Tunnel malposition** - anterior tibial = roof impingement, anterior femoral = rotational instability, may need two-stage revision **Patient Position**: Supine on standard operating table with operative leg in arthroscopic leg holder (allows full flexion to at least 130 degrees for hyperflexion during femoral tunnel drilling). Non-operative leg in lithotomy stirrup position or abducted and supported on leg holder. Operative leg hip flexed 30-45 degrees, externally rotated 10-15 degrees for comfortable access to medial knee. Thigh tourniquet applied high and proximal on thigh (rarely inflated - only if bleeding obscures visualization after attempting epinephrine infiltration with local anesthetic). Ensure leg holder allows easy adjustment of flexion angle throughout case (will need hyperflexion 110-120 degrees for femoral tunnel drilling, then various flexion angles for graft passage and fixation). Position patient on table to allow full knee flexion without leg holder contacting table edge or foot dropping off end. Fluoroscopy C-arm positioned on contralateral side if using fluoroscopic guidance for tunnel positioning (optional - most surgeons use arthroscopic visualization alone). Back table prepared for graft preparation (sizing tubes ranging 7-10mm, graft board with tensioning device to apply calibrated tension, suture materials including #2 non-absorbable braided suture for whipstitch, passing sutures). **Surgical Approach**: Arthroscopic approach via standard anterolateral (AL) and anteromedial (AM) portals for visualization and instrumentation. Anteromedial longitudinal 3-4cm incision on proximal medial tibia for hamstring graft harvest and tibial tunnel exit point. **Incision**: Portal incisions: (1) Anterolateral portal - 1cm proximal to joint line, just lateral to lateral border of patellar tendon (soft spot palpable with knee flexed 90 degrees). Standard 5mm skin incision. Entry point through lateral soft spot avoiding fat pad. (2) Anteromedial portal - established under direct arthroscopic visualization after AL portal created and arthroscope inserted. Position 2-3cm medial to medial border of patellar tendon, at joint line level. Use spinal needle under arthroscopic guidance to identify ideal trajectory before making portal (insert needle from proposed site, visualize trajectory arthroscopically, confirm needle can reach lateral wall of intercondylar notch and posterior horn of lateral meniscus). Adjust position until optimal trajectory confirmed. Make 5mm skin incision and create portal with trocar under arthroscopic visualization. Harvest incision: (3) Anteromedial tibial incision - vertical orientation parallel to tibial shaft, 3-4cm length, starting 2-2.5cm distal to joint line (palpate joint line with knee flexed), centered 2cm medial to tibial tubercle (landmarks: medial border of patellar tendon medially to tibial tubercle laterally - incision in between closer to tubercle). This incision serves dual purpose: hamstring graft harvest and tibial tunnel exit point. ### Step 1: Hamstring Graft Harvest and Preparation Hamstring Graft Harvest and Preparation: Position knee in 90 degrees flexion with foot flat on bed (relaxes hamstrings and pes anserinus tendons). Make 3-4cm vertical incision on anteromedial proximal tibia: start 2-2.5cm below joint line, 2cm medial to tibial tubercle (palpate tibial tubercle and medial patellar tendon border, mark midpoint). Incise skin and subcutaneous tissue carefully - IDENTIFY and PROTECT saphenous nerve (runs in subcutaneous fat medially, 1-2cm medial to incision) and infrapatellar branch (crosses incision site obliquely from superomedial to inferolateral, emerges 8-10cm above joint line). If nerve branches visualized, gently retract medially with vessel loop or Penrose drain. Use blunt finger dissection in subcutaneous layer rather than sharp dissection to reduce nerve injury risk. Incise sartorius fascia longitudinally (shiny white fascia overlying pes anserinus, easily identified). Identify PES ANSERINUS tendons beneath sartorius fascia (three tendons: gracilis most superficial and superior, semitendinosus deeper and inferior, sartorius most superficial and anterior): (1) Gracilis - most superficial and superior, appears as thin white rounded tendon approximately 3-4mm diameter; (2) Semitendinosus - deeper and inferior to gracilis, broader and thicker tendon approximately 5-6mm diameter. Palpate to differentiate (gracilis more superficial mobile, semitendinosus deeper). Bluntly dissect around each tendon with finger or small curved clamp (pass clamp around tendon separating from surrounding tissue). FREE TENDONS from surrounding tissue by finger dissection posteriorly (release posterior attachments and adhesions - critical for adequate stripping length). CRITICAL: Identify and divide any ACCESSORY DISTAL BANDS (semitendinosus often has 2-3 distal slips inserting separately on tibia - failure to release these accessory bands causes premature stripping with inadequate graft length). Use right-angle clamp to pass around each tendon proximally. Clamp each tendon with Kocher clamp or snap tendon stripper and transect at distal tibial insertion with scalpel (cut 1-2cm from tibial attachment to preserve enough distal stump for instrument grip). Pass closed tendon stripper (8mm diameter cylindrical stripper) over each freed tendon, advancing proximally along tendon while maintaining firm tension on distal end. Strip each tendon with steady firm pull (not yanking motion - slow steady pressure), protecting posterior structures by keeping stripper pressed against posterior tibia (do not allow stripper to migrate posteriorly into popliteal fossa where vascular structures located 3-4cm posterior). Typically strips to approximately 25-30cm length (may feel subtle 'pop' as muscle-tendon junction releases). Harvest both gracilis and semitendinosus tendons. Expected combined length greater than 24cm (minimum to create adequate quadruple-strand graft with sufficient length for tunnels and fixation - if less than 24cm may need to consider alternative graft or triple-strand technique). GRAFT PREPARATION (back table by assistant or surgeon): Clean each tendon of all muscle fibers and fascial tissue using scalpel and moist gauze (remove all non-tendinous tissue - muscle compromises graft strength). Measure each tendon length with ruler (typical 26-30cm each). Create QUADRUPLE-STRAND construct: fold gracilis tendon in half (creates 2 strands), fold semitendinosus in half (creates 2 strands), align all 4 free ends together (creates graft with 4 parallel strands - combined cross-sectional area provides strength). Whipstitch both ends with #2 non-absorbable braided suture (Fiberwire, Ethibond, TigerWire) using locking Krackow or baseball stitch pattern - minimum 2.5cm whipstitch length for each end (longer whipstitch distributes load and prevents pullout during tensioning). Alternative: running locked whipstitch technique. Ensure sutures tight and secure. SIZE GRAFT: Pass graft through cylindrical sizers (start at 7mm, progress through 7.5mm, 8mm, 8.5mm, 9mm, 10mm until graft no longer passes easily) - record final diameter that graft passes through. Ideal diameter 8-9mm (studies show less than 7mm has higher failure rate up to 2-3x, especially in young athletes; greater than 9mm acceptable and may be stronger but can be difficult to pass through tunnels). If less than 8mm diameter, consider triple-strand technique (fold one tendon in half, leave other straight creating 3 strands) or switching to BTB graft in high-demand athlete. Attach graft to TENSIONING BOARD: secure one end to fixed point on board, attach other end to weight typically 20-25 pounds / 90-110 Newtons (or use spring mechanism with calibrated tension). Allow graft to pre-tension for 10-15 minutes while performing arthroscopy and diagnostic evaluation (eliminates initial creep from tendon viscoelasticity - critical step). This pre-tensioning eliminates 1-2mm of initial graft elongation that would otherwise occur post-operatively causing laxity. Keep graft moist with saline-soaked sponge while on tensioning board. **Technical Tip**: EXAM KEY: 'Hamstring autograft has ADVANTAGES over BTB: (1) Lower anterior knee pain (5-10 percent versus 20 percent for BTB), (2) Lower kneeling pain (less than 10 percent versus 20-40 percent), (3) No patellar fracture risk (BTB has less than 1 percent risk but catastrophic), (4) Better cosmesis (smaller less visible scars), (5) Preserved bone stock for revision surgery (though hamstring not available for re-harvest). DISADVANTAGES: (1) Slower tendon-to-bone healing (6-8 weeks) versus BTB bone-to-bone healing (4 weeks) - protected rehabilitation first 6-8 weeks critical, (2) Potential hamstring weakness (10-20 percent persistent deficit in knee flexion peak torque though usually compensated by biceps femoris and clinically insignificant), (3) Higher tunnel widening rates (20-30 percent radiographically versus 10 percent BTB, though clinically insignificant in most cases), (4) Cannot use if previous hamstring harvest on same side. CRITICAL TECHNICAL POINTS for harvest: (1) SAPHENOUS NERVE protection - injury causes medial shin and foot numbness and painful neuroma. If nerve injured during harvest, must resect nerve end and bury in muscle proximally to prevent neuroma formation (neuroma requires reoperation for excision in 5-10 percent). (2) GRAFT LENGTH - must achieve greater than 24cm combined gracilis plus semitendinosus length to create adequate quadruple-strand graft with sufficient length for tunnels (femoral tunnel 30-35mm, intra-articular 30mm, tibial tunnel 40-50mm, fixation 20mm each end equals approximately 170-190mm required). If inadequate length (less than 24cm), consider triple-strand technique (fold one tendon, leave other straight) or switch to alternative graft (quadriceps tendon, BTB, allograft). (3) GRAFT DIAMETER - studies show less than 7mm diameter has significantly higher failure rates (Magnussen et al. AJSM 2012: grafts less than 7mm had 2.8x higher failure rate than 8mm or greater, especially in young athletes younger than 20 years and females). Aim for 8-9mm diameter. If less than 7.5mm in high-demand young athlete, consider switching to BTB or quadriceps tendon. (4) PRE-TENSIONING on graft board for 10 plus minutes under 20-25 pounds load eliminates early creep (viscoelastic tendon elongation under constant load) - without this step, graft will elongate 1-2mm post-operatively causing clinical laxity and potentially positive Lachman. ALTERNATIVE GRAFTS if hamstring unsuitable: BTB autograft (gold standard for high-level athletes in pivoting sports, faster healing with bone-to-bone interface, higher initial fixation strength, proven long-term outcomes 20 plus years, but higher donor site morbidity), Quadriceps tendon autograft (increasingly popular, bone plug on patellar end allows bone-to-bone femoral fixation, thicker graft typically 9-10mm, good option if previous hamstring harvest or large patient, intermediate donor site morbidity), Allograft (no donor site morbidity major advantage, unlimited availability for multiligament reconstruction, but slower incorporation 6-12 months, higher failure in young active patients younger than 25 years with 2-3x higher failure rate, disease transmission risk minimal 1 in 1.6 million with modern processing, good option for older lower-demand patients greater than 40 years or revision surgery).' - Saphenous nerve (1-2cm medial to incision) - injury causes numbness medial leg and foot, if transected forms painful neuroma requiring excision (5-10 percent if nerve cut). If nerve injured intra-operatively, must resect nerve end and bury proximally in muscle to prevent neuroma. - Infrapatellar branch saphenous nerve (crosses incision obliquely) - injury causes anterior knee numbness (common, 10-20 percent) usually resolves over 6-12 months but can be permanent (5-10 percent). - Popliteal vessels and tibial nerve (3-4cm posterior to posterior tibia at joint line level) - protected during stripping by keeping stripper pressed against tibia, risk if aggressive posterior dissection or stripper allowed to migrate posteriorly. - Inadequate graft length (less than 24cm combined) - cannot create adequate quadruple-strand construct, may need to switch grafts intra-operatively (quadriceps tendon, contralateral hamstring, allograft). Prevention: measure tendons before whipstitch, ensure all accessory distal bands released before stripping. - Semitendinosus accessory distal bands not released - if accessory slips not identified and divided, tendon strips prematurely yielding short inadequate length (15-20cm instead of 25-30cm). Prevention: blunt dissection distally to identify all slips, divide each one. - Premature tendon harvest before confirming ACL tear on arthroscopy - theoretical risk of harvesting graft when reconstruction not needed (always perform diagnostic arthroscopy and confirm ACL tear before harvesting, though rare to be wrong if good pre-operative MRI). ### Step 2: Arthroscopic Portal Establishment and Diagnostic Arthroscopy Arthroscopic Portal Establishment and Diagnostic Arthroscopy: Establish ANTEROLATERAL (AL) PORTAL first as primary viewing portal. Landmarks: 1cm proximal to joint line, just lateral to lateral edge of patellar tendon (soft spot palpable when knee flexed 90 degrees - depression lateral to patellar tendon). Infiltrate with local anesthetic with or without epinephrine (20ml 0.5 percent ropivacaine with 1:200,000 epinephrine - provides post-operative pain control and reduces intra-operative bleeding). Make 5mm vertical or transverse skin incision with #11 blade. Use sharp trocar or switching stick to penetrate capsule with knee flexed 90 degrees (aim toward intercondylar notch, feel 'pop' as trocar penetrates capsule and enters joint). Remove trocar and insert 30-degree arthroscope with inflow attached (gravity inflow or pump set to 40-60mmHg pressure). Perform SYSTEMATIC DIAGNOSTIC ARTHROSCOPY (follow consistent sequence every case to avoid missing pathology): (1) SUPRAPATELLAR POUCH - extend knee fully and advance scope proximally above patella into suprapatellar pouch. Inspect for loose bodies (osteochondral fragments, meniscal fragments), synovitis (thickened inflamed synovium suggests inflammatory arthritis or chronic ACL tear), visualization of quadriceps tendon (normally white glistening tendon), evaluate effusion character (hemarthrosis acute ACL injury, clear chronic, purulent suggests infection). (2) PATELLOFEMORAL JOINT - slowly flex and extend knee while viewing patellofemoral articulation. Track patella through range of motion. Assess articular cartilage of patella (medial facet, lateral facet, central ridge) and trochlea (medial facet, lateral facet, central groove) using Outerbridge classification (grade 0 normal, grade 1 softening, grade 2 superficial fissures, grade 3 deep fissures to subchondral bone, grade 4 exposed bone). Note any chondral lesions, tracking abnormalities, tilt or subluxation. (3) MEDIAL COMPARTMENT - slowly flex knee to approximately 30-40 degrees and apply valgus stress to open medial compartment (assistant pushes knee laterally or use valgus stress device). Visualize MEDIAL MENISCUS systematically: posterior horn (most common tear location with ACL injury - trapped during pivot shift mechanism), body, anterior horn. Probe meniscus at each segment with arthroscopic probe - assess stability and integrity. Look for vertical longitudinal tears (run parallel to circumferential fibers, bucket-handle configuration if displaced), radial tears (perpendicular to fibers), horizontal cleavage tears (split meniscus into superior and inferior leaves, degenerative pattern), meniscal root avulsions (detachment from tibial insertion). Test meniscal stability with probe (firmly attached at periphery equals normal, mobile fragment suggests tear). Assess medial tibial plateau and medial femoral condyle cartilage. (4) INTERCONDYLAR NOTCH - identify ACL remnant. Confirm ACL RUPTURE by visualizing disrupted fibers, empty footprints, "empty notch" sign. Assess stump location (femoral avulsion versus mid-substance tear versus tibial avulsion - mid-substance most common 70 percent), stump quality (acute tear with good quality hemorrhagic remnant versus chronic tear with poor quality friable stump), identify femoral and tibial footprints. Visualize PCL - should be intact and tight when knee flexed (bowstring appearance). Check PCL integrity with posterior drawer. Note lateral femoral condyle and posterior lateral tibial plateau bone bruising (contusion from pivot shift mechanism - hallmark of ACL injury). (5) LATERAL COMPARTMENT - extend knee slightly and apply varus stress to open lateral side (push knee medially). Visualize LATERAL MENISCUS systematically: posterior horn, popliteal hiatus (normal gap between posterior horn and body where popliteus tendon passes - do not mistake for tear), body, anterior horn. Lateral meniscus tears less common than medial with ACL injury but assess thoroughly. Use probe to test stability. Identify lateral recess, popliteus tendon (shiny white cord running posterolaterally), lateral meniscotibial ligament. Assess LCL insertion site, lateral capsule integrity. Assess lateral tibial plateau and lateral femoral condyle cartilage. (6) MEDIAL GUTTER - flex knee and advance scope medially posterior to medial femoral condyle. Recheck medial meniscus posterior horn from different viewing angle (better visualization of peripheral tears). Visualize posteromedial capsule. Establish ANTEROMEDIAL (AM) PORTAL under direct arthroscopic visualization (viewing from AL portal with knee flexed 90 degrees). Use spinal needle (18-gauge) to identify ideal trajectory - insert needle from proposed site (2-3cm medial to medial border of patellar tendon, at joint line level), advance into joint under arthroscopic visualization. Aim for center of joint with ability to reach lateral wall of intercondylar notch (for femoral tunnel drilling) and posterior horn of lateral meniscus (for instrumentation). Ideal AM portal position: just medial to medial edge of patellar tendon (2-3cm medial), at joint line level (avoid too high which causes intra-articular fat pad obstruction, avoid too low which limits access to posterior structures). Test trajectory with spinal needle - should reach posterolateral aspect of lateral wall (10-11 o'clock position on right knee) when knee hyperflexed to 110-120 degrees. Once trajectory confirmed with needle, remove needle and make 5mm skin incision at needle entry site. Penetrate capsule with trocar under arthroscopic visualization (watch trocar enter joint). This AM portal serves as primary WORKING PORTAL for all instrumentation and critical portal for femoral tunnel drilling (AM portal technique). DOCUMENT all pathology found (ACL tear, meniscal tears, cartilage lesions, other findings) - dictate findings or record in operative note for accurate documentation. **Technical Tip**: EXAM KEY: 'SYSTEMATIC arthroscopy following same sequence every case is ESSENTIAL to avoid missing associated pathology. Up to 50 percent of ACL ruptures have ASSOCIATED MENISCAL INJURY - medial meniscus posterior horn most common (25-30 percent) trapped during pivot shift mechanism causing peripheral longitudinal tear amenable to repair. Lateral meniscus injury also common (20-25 percent). Repairing concomitant meniscal tears improves healing dramatically (85-90 percent healing with ACL reconstruction versus 60-70 percent isolated meniscal repair) because ACL provides stable knee environment and hemarthrosis provides fibrin clot scaffold and growth factors. LATERAL FEMORAL CONDYLE bone bruising on MRI is hallmark of pivot shift injury mechanism (lateral femoral condyle impacts posterior lateral tibial plateau as tibia subluxates anteriorly then reduces - seen as bone marrow edema on T2 MRI sequences). Segond fracture (small lateral capsular avulsion fracture seen as thin fleck of bone lateral to tibial plateau on AP X-ray) is PATHOGNOMONIC for ACL tear - presence of Segond fracture equals 100 percent association with ACL tear. ACL STUMP characteristics: ACUTE tears (less than 6 weeks) have good quality remnant with hemorrhage and bleeding, CHRONIC tears (greater than 6 weeks) have poor quality friable stump. REMNANT PRESERVATION debate: Some surgeons preserve tibial remnant for potential proprioception benefit (mechanoreceptors in remnant may provide some residual proprioceptive feedback) and vascularity (blood vessels in remnant may enhance graft revascularization), others fully debride all remnant for better visualization of footprints and tunnel drilling. Evidence is MIXED - no clear outcome difference in Level 1 studies comparing remnant-preserving versus full debridement techniques. PORTAL PLACEMENT critical: AL portal too low causes Hoffa fat pad impingement (hypertrophic inflamed fat pad blocks view of lateral compartment and intercondylar notch). AM portal placement CRITICAL for femoral tunnel drilling - must have direct unobstructed line from portal to posterolateral wall of lateral femoral condyle when knee hyperflexed. Test AM portal trajectory with arthroscopic probe before committing to femoral tunnel (flex knee to 110-120 degrees, pass probe through AM portal, confirm probe reaches 10-11 o'clock position on lateral wall easily without impingement on roof or cartilage). If trajectory inadequate, make second AM portal in better position (abandon first portal). MENISCAL TEAR PATTERNS and repair potential: Bucket-handle equals longitudinal vertical tear with displaced fragment flipped into intercondylar notch (repair if peripheral red-red or red-white zone). Radial tear equals perpendicular to circumferential fibers reducing hoop stress mechanism (higher failure rate for repair 50-60 percent, but consider if peripheral). Horizontal cleavage equals degenerate pattern splitting meniscus into superior and inferior leaves (typically resect, poor healing potential). Root tear equals meniscal attachment to tibia torn (functionally equivalent to total meniscectomy as hoop stress mechanism lost - MUST repair with transtibial pullout technique, never resect roots). Ramp lesion equals peripheral longitudinal tear of medial meniscus posterior horn at meniscocapsular junction (associated with ACL injury, can only visualize from posteromedial viewing portal or by lifting posterior horn with probe, repair with all-inside devices or inside-out sutures).' - Iatrogenic cartilage damage from instruments (use gentle technique avoiding grinding instruments on cartilage surfaces, careful trocar insertion avoiding plunging into opposite side articular surface). - Missing associated pathology (meniscal tear, cartilage injury, other ligament injury, loose bodies) - systematic thorough approach prevents this, document all findings. - Portal placement too low for AL portal - fat pad impingement obscuring view, difficult to clear without aggressive fat pad resection which causes anterior knee pain and scarring. Prevention: portal 1cm above joint line in soft spot. - Portal placement too medial for AM portal - cannot reach lateral wall for femoral tunnel drilling, or trajectory causes roof impingement when trying to access posterolateral footprint. Prevention: test with spinal needle before making portal, confirm can reach 10-11 o'clock position on lateral wall with knee hyperflexed. - Instrument breakage in joint (shaver blades, radiofrequency probe tips, burr fragments) - rare but must document and retrieve all fragments arthroscopically if occurs (use grasper, small fragments may require mini-arthrotomy if cannot retrieve). Leaving metal fragments causes synovitis and potential loose body symptoms. - Excessive fluid extravasation into soft tissues (calf, thigh, posterior knee) from prolonged arthroscopy with high pump pressure - can cause compartment syndrome in severe cases. Prevention: use lowest effective pump pressure (40-60mmHg), minimize operative time, monitor for excessive swelling intra-operatively. ### Step 3: Meniscal Pathology Management (If Present) Meniscal Pathology Management (If Present): If meniscal tear identified on diagnostic arthroscopy, address BEFORE proceeding with ACL reconstruction (meniscal repair healing improved with stable knee from ACL reconstruction). DECISION: REPAIR versus RESECTION. INDICATIONS FOR REPAIR (favor repair whenever possible - meniscus preservation prevents osteoarthritis): (1) Peripheral location - RED-RED ZONE (outer one-third within 3-4mm of capsule, excellent blood supply from perimeniscal capillary plexus) or RED-WHITE ZONE (middle one-third 4-6mm from capsule, intermediate vascularity). WHITE-WHITE zone (inner one-third, avascular) cannot heal - resect unstable fragments only. (2) Tear pattern - vertical longitudinal (parallel to circumferential fibers, bucket-handle configuration) - IDEAL for repair with 85-90 percent healing rate. Radial tears (perpendicular to circumferential fibers) harder to repair with lower healing (50-60 percent) but consider if peripheral (radial tears disrupt hoop stress mechanism). Horizontal cleavage tears (degenerative pattern splitting meniscus horizontally) - typically resect (poor healing 20-30 percent). Complex multiplanar tears - usually resect (poor healing). (3) Tear acuity - acute traumatic tears in young patients heal better (80-90 percent) than chronic degenerative tears in older patients (50-60 percent). (4) Concomitant ACL reconstruction - dramatically improves meniscal repair healing rates from 60-70 percent (isolated meniscal repair) to 85-90 percent (repair with ACL) due to stable knee environment reducing shear forces and hemarthrosis providing fibrin clot and growth factors. CONTRAINDICATIONS TO REPAIR: Chronic degenerative tears (frayed edges, poor tissue quality), white-white zone central location (avascular, no healing potential), complex multiplanar tears (difficult to repair, poor outcomes), extensive meniscal damage (greater than 50 percent destroyed, insufficient remaining meniscus), poor tissue quality (thinned, attenuated), patient factors (non-compliant with protected rehabilitation, elderly sedentary). REPAIR TECHNIQUE using ALL-INSIDE devices (most common contemporary technique): (1) PREPARE tear site - use motorized shaver or meniscal rasp to FRESHEN/ABRADE edges of tear on both superior and inferior leaves (remove fibrocartilage surface layer exposing underlying vascular tissue, promotes bleeding and healing response). Use rasp or curette to abrade adjacent synovial capsule (enhance vascularity and bleeding). Some surgeons make small trephination holes across tear with spinal needle (channel blood from capsule into tear site promoting fibrin clot formation). Apply fibrin clot (take blood from arthroscopic portal, inject into tear site to provide scaffold for healing). (2) REDUCE displaced fragments - use arthroscopic probe, meniscal grasper, or spinal needle to reduce displaced bucket-handle fragment back to anatomic position (align edges perfectly for healing). Hold reduction with probe while inserting repair device. (3) SELECT all-inside meniscal repair device (pre-loaded sutures with anchors deployed extra-articularly on capsular side): FasT-Fix (Smith and Nephew - two anchors connected by suture), Omnispan (Arthrex - adjustable suture bridge), Sequent (ConMed - bio-absorbable anchors), Crossfix (Cayenne Medical - knotless adjustable), Ultra FasT-Fix (self-adjusting implant). (4) INSERT device through working portal (typically AM portal for medial meniscus, AL portal for lateral meniscus). Insert device needle through meniscus body on superior surface, pass across tear, exit on capsular (peripheral) side of meniscus on inferior surface. DEPLOY anchors on extra-articular capsular side (outside meniscus in synovial tissue - anchors grab capsule). Withdraw device needle leaving suture across tear connecting anchors. (5) TENSION and TIE suture - pull suture to bring tear edges together (reduce tear), tie arthroscopic knot or use self-locking mechanism depending on device (most modern devices self-adjust and lock). Place MULTIPLE repair devices along length of tear spaced 4-5mm apart (typical tear requires 2-4 devices depending on length - 1-2cm tear needs 2 devices, 3-4cm bucket-handle needs 4 devices). Start posteriorly and work anteriorly. (6) CHECK stability of repair with probe - meniscus should be stable to probing, tear edges well-opposed and reduced. No gap at repair site. ALTERNATIVE TECHNIQUES: INSIDE-OUT repair (gold standard for posterior horn tears, provides strongest repair but requires posteromedial or posterolateral safety incisions with retractors to protect neurovascular structures - more invasive, risk of nerve injury): Pass long flexible needles with sutures from inside joint through meniscus and capsule to outside, retrieve sutures through safety incision, tie over capsule extra-articularly. Requires posteromedial incision for medial meniscus (protect saphenous nerve and vein) or posterolateral incision for lateral meniscus (protect common peroneal nerve, popliteal vessels). OUTSIDE-IN repair (for anterior horn tears accessible from anterior): Pass sutures from outside through capsule and meniscus to inside joint, retrieve intra-articularly, tie arthroscopically or extra-articularly. POST-OPERATIVE IMPLICATIONS of meniscal repair: Requires MODIFIED REHABILITATION protocol - (1) Limit deep flexion greater than 90 degrees for first 6 weeks (protects posterior horn repairs from excessive hoop stress), (2) Protected weight-bearing with crutches for 4-6 weeks (partial weight-bearing 20-50 percent or toe-touch depending on surgeon preference and tear location), (3) Hinged brace locked at 0-90 degrees for 4-6 weeks (prevents excessive flexion), (4) Delayed return to impact activities (running 4-5 months versus 3-4 months isolated ACL), (5) Delayed return to sport (12-15 months versus 9-12 months isolated ACL), (6) Repair failure rate 10-15 percent with protected rehabilitation (versus 20-40 percent if not protected) - manifests as recurrent mechanical symptoms (catching, locking, pain) requiring subsequent meniscectomy. Counsel patient on importance of compliance with protected rehabilitation to maximize repair healing. **Technical Tip**: EXAM KEY: 'MENISCAL REPAIR versus RESECTION is one of most important surgical decisions impacting long-term outcomes. MENISCUS FUNCTION critical for joint health: (1) Load distribution (menisci transmit 50-70 percent of load in extension, up to 85 percent in flexion - meniscectomy increases contact stress 2-3x leading to accelerated cartilage degeneration), (2) Shock absorption (viscoelastic properties dissipate energy), (3) Joint stability (secondary stabilizer to ACL - meniscectomy increases anterior tibial translation 5-10 percent), (4) Proprioception (mechanoreceptors provide joint position sense). RESECTION consequences: Partial meniscectomy removing only unstable torn fragment acceptable if limited (less than 25 percent removed), Total or subtotal meniscectomy (greater than 50 percent removed) leads to osteoarthritis in 80-90 percent at 10-20 years (Fairbank changes on X-ray: joint space narrowing, flattening of femoral condyle, osteophyte formation). REPAIR HEALING RATES by technique and associated surgery: Isolated meniscal repair 60-70 percent healing, Meniscal repair with ACL reconstruction 85-90 percent healing (WHY: Stable knee from ACL reduces shear forces on repair, Hemarthrosis from ACL drilling provides fibrin clot scaffold and growth factors promoting healing, Marrow stimulation from tunnel drilling releases mesenchymal stem cells and growth factors). MENISCAL ROOT TEARS (posterior root avulsion especially medial meniscus): Functionally equivalent to total meniscectomy even though meniscal body intact (loss of hoop stress mechanism - meniscus cannot function without secure tibial attachment, meniscus extrudes peripherally with loading). MUST REPAIR with TRANSTIBIAL PULLOUT technique: drill tunnel from anatomic tibial root footprint (7-9mm posterior to posterior edge of medial tibial plateau for medial meniscus root) to anterior tibia exit, pass non-absorbable suture (#2 Fiberwire or tape) through meniscal root tissue using Krakow or locking stitch, pull suture through tunnel exiting anteriorly, tie over bone bridge or cortical button on anterior tibia with knee at 30 degrees flexion. Root repair healing 70-80 percent (reduces extrusion, improves contact mechanics). NEVER resect root tears (creates same outcome as total meniscectomy). EXAM QUESTION SETUP: Examiner asks During ACL reconstruction you identify a medial meniscus posterior horn vertical longitudinal tear extending 2cm along the peripheral rim in the red-red zone. What do you do? ANSWER: I would REPAIR this tear. It meets ideal criteria for repair: peripheral red-red zone location with good blood supply, vertical longitudinal tear pattern (ideal for repair), 2cm length (manageable), in setting of ACL reconstruction (dramatically enhances healing from 60-70 percent isolated to 85-90 percent with ACL). I would use all-inside meniscal repair devices placing 2-3 devices along tear after freshening edges with rasp and abrading capsule. This approach preserves meniscal function reducing long-term osteoarthritis risk from 80-90 percent with resection to 10-20 percent with successful repair. Post-operatively requires modified rehabilitation: limit flexion greater than 90 degrees for 6 weeks, partial weight-bearing 4-6 weeks, delayed return to sport 12-15 months. LATERAL MENISCUS CONSIDERATIONS: Popliteal hiatus naturally separates posterior horn from body (popliteus tendon passes through hiatus) - do not mistake normal gap for tear. Common peroneal nerve at high risk with lateral meniscus inside-out repair technique (wraps around fibular neck 2-3cm distal to joint line in posterolateral corner). All-inside devices much safer than inside-out for lateral meniscus (avoid nerve exposure and dissection entirely).' - SAPHENOUS NERVE injury with medial meniscus inside-out repair (runs posteromedially 1-2cm posterior to MCL at joint line level) - causes medial shin and foot numbness (10-20 percent if nerve injured), neuroma if transected. Prevention: use posteromedial safety incision with retraction of nerve medially (identify nerve in subcutaneous tissue, retract with vessel loop), or use all-inside devices avoiding nerve exposure entirely. - COMMON PERONEAL NERVE injury with lateral meniscus inside-out repair (wraps around fibular neck posterolaterally 2-3cm from joint line) - causes FOOT DROP (loss of dorsiflexion and eversion from deep and superficial peroneal nerve branches), numbness on dorsum of foot. Devastating complication. Prevention: use posterolateral safety incision with nerve identification and protection (palpate fibular neck, make incision over lateral head of gastrocnemius, develop interval between biceps femoris and gastrocnemius, identify and protect nerve), or preferably use all-inside devices avoiding nerve dissection. If foot drop identified post-operatively, immediate EMG/NCS and neurology consultation - neurapraxia may recover over 3-6 months, complete transection may need nerve exploration and grafting with poor recovery. - Implant-related synovitis with all-inside devices (suture knots or bio-absorbable anchors can cause irritation if prominent intra-articularly or if inflammatory reaction to material) - causes effusion, pain, catching sensation. Usually self-limited resolving over 6-12 months, but may require arthroscopic removal of prominent devices (2-3 percent). Prevention: ensure anchors deploy extra-articularly on capsule (not intra-articularly), trim suture tails short, use lowest profile devices. - Repair failure (10-30 percent depending on location, pattern, technique, and rehabilitation compliance) - manifests as recurrent mechanical symptoms (catching, locking, pain) starting 3-12 months post-operatively. MRI shows persistent gap at repair site or recurrent tear. May require subsequent arthroscopic meniscectomy (resect failed repair). Prevention: select appropriate tears for repair (peripheral, vertical longitudinal, acute), use proper technique (freshen edges, multiple devices, good reduction), enforce protected rehabilitation (no deep flexion greater than 90 degrees for 6 weeks, partial weight-bearing 4-6 weeks). - Device malfunction (needle breakage during insertion, anchor deployment failure, suture breakage) - occurs in 1-2 percent of devices. Keep extra backup devices available. If needle breaks, retrieve fragment arthroscopically with grasper. If anchor fails to deploy, remove device and use new one. - Chondral damage during repair (needle passes through articular cartilage if angled incorrectly) - can create iatrogenic cartilage defect. Prevention: angle device parallel to tibial plateau aiming from superior (articular) surface of meniscus to inferior (capsular) surface, avoid steep angles that penetrate cartilage. ### Step 4: ACL Remnant Debridement and Notchplasty (If Needed) ACL Remnant Debridement and Notchplasty (If Needed): GOAL: Adequately debride ACL remnant to visualize anatomic femoral and tibial footprints for accurate tunnel placement, while potentially preserving some remnant for proprioception and vascularity if using remnant-preserving technique. Use motorized shaver (4.0-5.5mm aggressive full-radius blade) and radiofrequency ablation device. Viewing from AL portal, working through AM portal. IDENTIFY KEY ANATOMIC LANDMARKS for femoral footprint: (1) LATERAL INTERCONDYLAR RIDGE (also called Resident's Ridge) - vertical bony ridge on lateral wall of intercondylar notch (medial aspect of lateral femoral condyle), marks ANTERIOR border of femoral ACL footprint. Easily palpated with probe. (2) OVER-THE-TOP POSITION - most posterior-superior point on lateral wall where lateral femoral condyle curves over posteriorly to become posterior condyle (no articular cartilage at this transition point). Marks POSTERIOR boundary of femoral footprint. Identified by passing probe over top of condyle posteriorly (probe drops off posterior edge into posterior fossa). (3) BIFURCATE RIDGE - subtle horizontal ridge separating anteromedial (AM) bundle footprint (inferior) from posterolateral (PL) bundle footprint (superior) on femoral side - can be subtle or absent, not always visualized. (4) LATERAL FEMORAL CONDYLE articular cartilage margin - marks superior/proximal boundary of footprint (femoral footprint located 2-3mm distal to inferior edge of weight-bearing articular cartilage). DEBRIDE ACL REMNANT: Remove torn ACL fibers with motorized shaver using aggressive cutting technique (shaver toward tissue) - remove stump from intercondylar notch to expose footprints. Consider preserving some tibial stump if good quality and not obscuring view (remnant-preserving technique may provide proprioception and vascularity benefits, though evidence mixed). Use radiofrequency ablation device to shrink and remove soft tissue and achieve hemostasis (stop bleeding for better visualization). Goal is clear visualization of both FEMORAL and TIBIAL footprints without obscuring tissue. TIBIAL FOOTPRINT identification: Located on tibial plateau posterior to anterior horn of lateral meniscus, anterior and slightly lateral to PCL tibial insertion, medial to lateral tibial spine, centered approximately at junction of anterior one-third and posterior two-thirds of tibia in AP dimension. Classic teaching: 7mm anterior to posterior tibial cortex on lateral fluoroscopic view (though arthroscopic visualization more accurate). Can mark footprint center with electrocautery tip or microfracture awl for reference during tibial tunnel drilling. ASSESS INTERCONDYLAR NOTCH WIDTH: Flex knee to 90 degrees and view intercondylar notch from AL portal. Assess if notch is narrow/stenotic which may cause graft impingement on lateral wall or roof. Historic teaching: Perform routine notchplasty on all ACL reconstructions. MODERN approach: Notchplasty often NOT needed if using anatomic tunnel position with AM portal femoral tunnel technique (creates more posterior oblique tunnel with less impingement risk than anterior vertical tunnel from old transtibial technique). INDICATIONS FOR NOTCHPLASTY (selective, not routine): (1) Obvious notch stenosis on MRI or arthroscopy (Blumensaat line to intercondylar notch width ratio less than 0.2 on lateral X-ray indicates stenosis), (2) Visible graft impingement on lateral wall during ROM testing (simulate graft with probe - if probe rubs on lateral wall during extension to flexion ROM, indicates impingement requiring notchplasty), (3) Narrow notch preventing adequate footprint visualization (cannot see entire femoral footprint due to tight space). NOTCHPLASTY TECHNIQUE (if indicated): Use motorized burr (4.0-5.5mm round or oval burr) or osteotome. Remove bone from LATERAL WALL of intercondylar notch (medial aspect of lateral femoral condyle) - NOT from medial wall (lateral aspect of medial femoral condyle) or roof (distal femur). Remove bone CONSERVATIVELY - goal is relieve impingement without creating massive defect, not create wide notch. Remove anterior osteophytes if present (common in chronic ACL deficiency). Typical bone removal: 3-5mm width from lateral wall. Use burr with high speed and light pressure avoiding plunging (control burr carefully to prevent skipping onto articular cartilage or diving too deep). Work from anterior to posterior along lateral wall. CHECK IMPINGEMENT after notchplasty: Test with knee in full extension (bring knee to 0 degrees while viewing from AL portal) - use probe to simulate where graft will be positioned, check clearance between graft position and lateral wall/roof. Probe should not contact lateral wall or roof throughout ROM from full extension to 90 degrees flexion. AVOID EXCESSIVE NOTCHPLASTY: Over-resection weakens lateral femoral condyle (can lead to lateral wall fracture during tunnel drilling 1-2 percent), risks posterior cortex blowout if burring too far posterior (removes bone posterior to femoral footprint compromising posterior wall of femoral tunnel), removes bone stock needed for femoral tunnel (adequate bone required for tunnel and fixation). Contemporary trend: MINIMAL or NO notchplasty with anatomic AM portal technique (90 percent of cases do not require notchplasty - only perform if clear indication for impingement or visualization). Final check: Visualize both femoral and tibial footprints clearly marked and ready for tunnel drilling. **Technical Tip**: EXAM KEY: 'Notchplasty is CONTROVERSIAL topic with significant evolution in thinking over past 20 years. HISTORIC APPROACH (1980s-2000s): Aggressive routine notchplasty performed on all ACL reconstructions to prevent graft impingement. Rationale: Notch stenosis associated with ACL tears (narrow notch may be anatomic predisposing factor for ACL injury - smaller ACL cross-sectional area), femoral tunnel positioned anteriorly with transtibial technique prone to impingement, belief that wider notch better for graft. Technique: Remove 5-10mm of bone from lateral wall creating wide notch. MODERN APPROACH (2010s-present): Notchplasty often UNNECESSARY with anatomic AM portal femoral tunnel technique. Selective notchplasty only if clear indication. WHY change: Transtibial femoral tunnel technique (old standard) created anterior-vertical femoral tunnel at 11-12 o'clock position (right knee) prone to impingement on roof and lateral wall requiring notchplasty for clearance. AM portal technique (current standard) creates posterior-oblique femoral tunnel at 10-11 o'clock position with natural clearance from roof and lateral wall (graft positioned more posteriorly away from impingement sites). Studies show notchplasty not needed in 80-90 percent of anatomic AM portal ACL reconstructions. NOTCH STENOSIS measurement: Blumensaat line (roof of intercondylar notch on lateral X-ray) to intercondylar notch width ratio on AP X-ray. Ratio less than 0.2 suggests stenosis (notch width less than 20 percent of Blumensaat line length). Females have narrower notches on average (potential risk factor for higher ACL injury rate in females - smaller notch equals smaller ACL cross-sectional area and higher stress). GRAFT IMPINGEMENT CONSEQUENCES if not addressed: (1) EXTENSION LOSS (mechanical block preventing terminal extension) - WORST complication of ACL reconstruction causing quadriceps shutdown, patellofemoral pain, patellofemoral arthritis. (2) CYCLOPS LESION formation (anterior ACL stump or graft impingement stimulates fibrous nodule proliferation creating focal mass blocking extension). (3) Graft ABRASION and failure (repetitive rubbing of graft on bone causes fiber disruption and weakening leading to graft failure over months to years). CRITICAL POINT: Achieving FULL EXTENSION (0 degrees) before leaving OR is NON-NEGOTIABLE checkpoint. Extension loss causes quad shutdown (neurologic inhibition - inability to fully activate quadriceps if knee not fully extended), patellofemoral overload pain, accelerated patellofemoral arthritis (increased contact stress from altered mechanics). If extension loss present at end of case, MUST identify cause and address before closing: (1) Impingement from tibial tunnel too anterior or inadequate notchplasty (perform notchplasty to clear impingement), (2) Cyclops lesion from inadequate ACL stump debridement (debride residual stump), (3) Graft over-constraint from tibial fixation too tight (revise tibial fixation - back out screw, reduce tension, re-fix at correct tension), (4) Intra-articular adhesions from prolonged manipulation (debride scar tissue), (5) Large hemarthrosis (aspirate blood from joint). Never leave OR accepting greater than 2-3 degrees extension loss - must achieve 0 degrees. EXAM SETUP: Post-operatively your patient has loss of terminal extension and reports anterior knee clicking. MRI shows soft tissue nodule anterior to ACL graft. What is this and how do you manage it? ANSWER: This is CYCLOPS LESION - focal fibrous nodule forming from impingement of residual ACL stump or anterior graft on roof of intercondylar notch. Causes mechanical block to extension (firm endpoint) and clicking sensation as lesion catches on roof. Managed with arthroscopic excision of nodule which typically restores extension immediately (remove nodule with shaver and radiofrequency device, may need notchplasty if impingement contributing). Prevention involves adequate ACL stump debridement at index surgery (remove anterior stump), notchplasty if narrow notch or impingement risk, ensuring full extension (0 degrees) before closing at index surgery. Post-excision requires aggressive extension exercises (prone hangs, extension splinting) to maintain extension and prevent recurrence (recurrence rare less than 5 percent if complete excision).' - Posterior femoral cortex BLOWOUT from aggressive notchplasty (burring too far posterior removes bone posterior to femoral footprint) - loss of posterior wall prevents interference screw femoral fixation as screw relies on posterior wall. Occurs in 5-10 percent if notchplasty too aggressive. MANAGEMENT: If identified during notchplasty before femoral tunnel drilling, avoid drilling tunnel too posterior (maintain 6-7mm anterior to over-the-top), use suspensory button fixation which relies on lateral cortex not posterior wall. If identified after femoral tunnel drilling (probe passes through posterior wall into posterior fossa), switch to button fixation (Endobutton, TightRope - does not require posterior wall integrity). Outcome equivalent to intact posterior wall if button used appropriately. - Lateral femoral condyle FRACTURE from excessive lateral wall resection (removing greater than 5-7mm weakens condyle structurally) - rare but catastrophic complication. Presents as visible crack or fracture line on lateral wall during or after notchplasty/tunnel drilling. MANAGEMENT: If identified, may need screw fixation of fracture (percutaneous or mini-open lateral approach), consider aborting ACL reconstruction and staging after fracture heals (6-12 weeks), or proceed with caution using button fixation avoiding additional stress. Prevention: conservative notchplasty (3-5mm maximum), careful burring technique. - Graft IMPINGEMENT if inadequate notch clearance despite performing procedure - causes extension loss, graft failure over time. MUST identify during final ROM check before closing (arthroscopically visualize graft through full ROM, check for any contact between graft and roof or lateral wall). If impingement present post-notchplasty, perform additional notchplasty to clear. Do not leave OR with graft impingement. - CYCLOPS LESION formation from inadequate anterior ACL stump debridement - residual stump left anteriorly in intercondylar notch undergoes fibrous proliferation from repeated impingement creating nodule. Causes extension loss starting 6 weeks to 6 months post-op. Prevention: adequate debridement of ACL stump especially anterior portion, notchplasty if narrow notch, confirm full extension before closing. Treatment: arthroscopic excision of cyclops lesion restoring extension immediately. - Articular cartilage damage to medial or lateral femoral condyle from burr (burr skips onto articular surface or controlled improperly) - creates iatrogenic chondral defect. Prevention: careful burring technique on lateral wall only (not medial wall, not roof), high speed with light pressure, avoid articular surfaces, work away from cartilage edges. If cartilage damage occurs, document and consider treatment based on size (small less than 1cm may observe, larger may need microfracture or cartilage restoration). ### Step 5: Femoral Tunnel Creation - Anatomic Anteromedial Portal Technique Femoral Tunnel Creation - Anatomic Anteromedial Portal Technique: This step is CRITICAL for ACL reconstruction success determining anatomic graft position and long-term outcomes. Goal: Create femoral tunnel with intra-articular aperture positioned at CENTER of native ACL femoral footprint (specifically AM bundle footprint center) for anatomic graft orientation and function. TECHNIQUE: ANTEROMEDIAL PORTAL technique for independent femoral tunnel drilling (NOT transtibial technique which is outdated and non-anatomic). POSITIONING: Flex knee to 110-120 degrees of hyperflexion (relaxes superficial capsular fibers improving access to posterior footprint on lateral wall, opens intercondylar notch allowing better visualization and instrumentation). May need assistant to hold knee in hyperflexion or use foot support. Alternative: figure-4 position (knee flexed 90 degrees, hip flexed 45 degrees and abducted, foot externally rotated creating frog-leg position). FEMORAL FOOTPRINT IDENTIFICATION (viewing from AL portal, working through AM portal with knee hyperflexed): Footprint located on LATERAL WALL of intercondylar notch (medial aspect of lateral femoral condyle). Use probe to identify BOUNDARIES: Anterior boundary equals Resident's ridge (lateral intercondylar ridge - easily palpable vertical ridge), Posterior boundary equals over-the-top position (most posterior-superior point where condyle curves posteriorly - probe drops off edge, target position is 6-7mm ANTERIOR to this critical measurement), Superior boundary equals articular cartilage margin (inferior edge of weight-bearing cartilage - target position is 2-3mm INFERIOR to cartilage edge to avoid creating chondral defect), Inferior boundary equals roof of intercondylar notch. CLOCK FACE REFERENCE system: Viewing lateral wall en face (looking directly at wall) with knee flexed. RIGHT KNEE equals 10-11 o'clock position (12 o'clock equals superior/proximal, 3 o'clock equals posterior, 6 o'clock equals inferior/distal, 9 o'clock equals anterior). Target center of AM bundle footprint at 10:30 position. LEFT KNEE equals 1-2 o'clock position (mirror image of right knee - 12 o'clock equals superior, 9 o'clock equals posterior, 6 o'clock equals inferior, 3 o'clock equals anterior). Target 1:30 position. This represents POSTEROLATERAL position on lateral wall (posterior and low on footprint). CENTER OF FOOTPRINT marking: Use arthroscopic ruler or depth gauge to measure 6-7mm anterior to over-the-top position (critical measurement - less than 6mm risks posterior wall blowout, greater than 7mm creates anterior non-anatomic tunnel), measure 2-3mm inferior to articular cartilage margin. Mark center point with electrocautery tip or microfracture awl creating small divot for reference (helps guide wire placement). GUIDEWIRE PLACEMENT using offset femoral guide: Insert offset femoral guide through AM portal with knee in hyperflexion. Offset guide has adjustable tip offset (typically 6-7mm offset) allowing guidewire to exit on lateral femoral cortex. Position guide tip at marked center of footprint (10:30 right knee, 1:30 left knee). Guide should sit flush against lateral wall. Angle guide to aim from AM portal entry through marked footprint center toward lateral femoral cortex (will exit on lateral thigh). Alternative: use flexible curved reamer system (FlipCutter, Retro-Drill) which reams from inside-out without needing outside-in guidewire. CRITICAL CHECKPOINT before drilling guidewire: Confirm position arthroscopically - guide tip should be at marked center (6-7mm anterior to over-the-top measured with ruler, 2-3mm inferior to cartilage, centered between resident's ridge anteriorly and over-the-top posteriorly). If position incorrect, adjust guide before drilling. Can use second spinal needle through AM portal to mark ideal position and compare to guide position. DRILL GUIDEWIRE: Once position confirmed, drill 2.4mm smooth guidewire through guide from inside (footprint center) toward outside (lateral femoral cortex) - will exit on lateral thigh. Advance wire until tip penetrates lateral cortex and exits skin (may feel subtle give as wire penetrates cortex). Remove guide leaving wire in place. CONFIRM WIRE POSITION arthroscopically: Wire should enter joint at marked footprint center (10-11 o'clock right knee). If wire malpositioned (too anterior toward 11-12 o'clock or too posterior toward 9-10 o'clock or too superior toward cartilage), REMOVE wire and re-drill correctly (do not proceed with malpositioned wire - will create non-anatomic tunnel with poor outcomes). Can check wire position with lateral fluoroscopy (wire should be posterior in intercondylar notch, 6-7mm from over-the-top). MEASURE FEMORAL TUNNEL LENGTH: Use depth gauge over guidewire - insert depth gauge through AM portal, pass over wire to lateral femoral cortex, measure from intra-articular aperture (footprint center) to lateral cortex. Need MINIMUM 25-30mm tunnel length for adequate fixation (short tunnels less than 25mm risk button pulling through cortex or inadequate screw purchase). Ideal 30-35mm length. Record length (will need for selecting fixation devices). If tunnel too short (less than 25mm from small patient or wire angled too obliquely), may need to adjust wire angle or accept short tunnel and plan fixation accordingly (use longer button loop or interference screw femoral fixation). REAM FEMORAL TUNNEL using cannulated reamer over guidewire: Select cannulated reamer matching graft diameter (typically 8mm or 9mm if graft is 8-9mm diameter, some surgeons ream 0.5mm larger for easier graft passage). For outside-in technique: Insert acorn-shaped reamer from outside (lateral femoral cortex) over wire toward inside (joint). Acorn reamer creates smooth rounded tunnel aperture preventing graft abrasion on sharp bone edges. Advance reamer to pre-marked depth on reamer (based on tunnel length measurement) - typical depth 30-35mm from lateral cortex. Use power drill on low speed setting (not high speed which generates heat). Watch reamer enter joint arthroscopically from AL portal (should see reamer appear at marked footprint center). Ream to full depth. Alternative for inside-out flexible reamer: Advance flexible curved reamer through AM portal over guidewire, ream from inside toward outside (self-drilling and reaming). CRITICAL during reaming: Preserve POSTERIOR WALL integrity - must maintain 1-2mm bone thickness of posterior femoral cortex. Watch for posterior wall breakthrough arthroscopically (should not see reamer penetrate posteriorly into posterior fossa). If posterior wall intact, can use interference screw or button fixation. If posterior wall blowout occurs (see reamer or probe pass through posterior wall into fossa), requires button fixation relying on lateral cortex only (cannot use interference screw). Check posterior wall after reaming with probe or depth gauge (pass probe along posterior tunnel wall - should feel solid bone, probe should not pass through wall into posterior space). REMOVE BONE DEBRIS from tunnel: Back reamer out slowly while still rotating (clears bone chips from tunnel and flutes). Use motorized shaver to remove remaining bone debris from tunnel aperture and joint. Irrigate copiously with arthroscopic pump. FINAL CHECK of femoral tunnel: Pass probe through tunnel from joint to lateral cortex - should feel smooth cylindrical tunnel, intact posterior wall (probe does not pass through posteriorly), tunnel positioned at anatomic footprint center (10-11 o'clock right knee), tunnel length 30-35mm adequate for fixation, tunnel diameter matches graft (passes probe of same diameter as graft easily). Record femoral tunnel parameters (length, diameter, position) in operative note. **Technical Tip**: EXAM KEY: 'ANATOMIC AM PORTAL TECHNIQUE represents major paradigm shift in ACL surgery over past 15-20 years and is current GOLD STANDARD. HISTORICAL EVOLUTION critical to understand: (1) 1980s-early 2000s: TRANSTIBIAL TECHNIQUE was standard approach - drilled femoral tunnel THROUGH tibial tunnel in one pass using transtibial guide. ADVANTAGES: Technically easier with shorter learning curve, single continuous tunnel drilling, good for teaching residents. DISADVANTAGES: Geometric constraints forced femoral tunnel ANTERIOR and VERTICAL (non-anatomic position typically 11-12 o'clock right knee rather than anatomic 10-11 o'clock) with poor rotational stability especially pivot shift control. CONSEQUENCE: High rates of positive residual pivot shift (20-30 percent), graft failure in pivoting sports (10-15 percent at 5 years), patient dissatisfaction, inferior outcomes. Transtibial technique largely abandoned by most surgeons. (2) Mid-2000s-present: AM PORTAL TECHNIQUE introduced by European surgeons and adopted worldwide - femoral tunnel drilled INDEPENDENTLY through AM portal separate from tibial tunnel, allows TRUE ANATOMIC FOOTPRINT positioning (10-11 o'clock right knee representing POSTERIOR position on lateral wall). Requires hyperflexion (110-120 degrees) for access. ADVANTAGES: Better replicates native ACL anatomy (posterior oblique tunnel orientation), superior rotational stability (better restraint to pivot shift from posterolateral graft position), lower failure rates (5-10 percent at 5 years), better patient-reported outcomes, higher return to sport rates, more anatomic knee kinematics on motion analysis. DISADVANTAGES: Technically more challenging with steeper learning curve, requires good arthroscopic skills and spatial orientation, hyperflexion may be difficult in obese patient or stiff knee, risk of posterior wall blowout if tunnel placed too posterior (5-10 percent), slightly longer operative time. EVIDENCE supporting AM portal superiority: Multiple Level 1 RCTs and meta-analyses show AM portal technique superior to transtibial for rotational stability (negative pivot shift 90-95 percent versus 70-80 percent), IKDC scores (90 versus 83), patient satisfaction (88 percent versus 78 percent), return to sport rates (75 percent versus 65 percent). FEMORAL FOOTPRINT DETAILED ANATOMY: ACL has TWO BUNDLES on femoral side - Anteromedial (AM) bundle (larger, 60 percent of total ACL cross-sectional area, anterior and inferior on footprint, primary restraint to anterior tibial translation especially in flexion, taut in flexion 90-120 degrees and relatively relaxed in extension), Posterolateral (PL) bundle (smaller, 40 percent, posterior and superior on footprint, primary restraint to rotational loads and anterior translation near extension, taut in extension 0-30 degrees and relaxed in flexion). SINGLE-BUNDLE RECONSTRUCTION (current standard) targets AM bundle footprint center at 10:30 (right knee) or 1:30 (left knee) which provides best overall stability for most patients (addresses both anterior translation and rotational instability). DOUBLE-BUNDLE RECONSTRUCTION (separate AM and PL bundle tunnels and grafts) theoretically more anatomic replicating both bundles, but multiple Level 1 RCTs show NO significant advantage over anatomic single-bundle reconstruction for clinical outcomes (IKDC scores, return to sport, graft failure rates all equivalent) - double-bundle more complex, higher cost, technically demanding, not routinely indicated. Most surgeons use anatomic single-bundle targeting AM footprint center. CLOCK FACE REFERENCE SYSTEM for describing femoral tunnel position: Viewing lateral wall of intercondylar notch en face (looking directly at wall) with knee flexed - RIGHT knee: 12:00 equals superior/proximal toward cartilage, 3:00 equals posterior toward over-the-top, 6:00 equals inferior/distal toward roof, 9:00 equals anterior toward resident's ridge. ACL femoral footprint occupies roughly 9:30-2:00 region (shallow C-shape). AM bundle center approximately 10:30. PL bundle center approximately 1:00. Transtibial tunnel typically ended up at 11:00-12:00 (too anterior and vertical creating non-anatomic graft). AM portal technique achieves 10:00-11:00 (anatomic posterolateral position). LEFT knee is mirror image: 12:00 equals superior, 9:00 equals posterior, 6:00 equals inferior, 3:00 equals anterior. Target 1:00-2:00 for anatomic position. POSTERIOR WALL BLOWOUT management: Occurs if femoral tunnel drilled too close to over-the-top position (less than 6mm anterior) or over-reaming with aggressive technique. Incidence 5-10 percent even in experienced hands. RECOGNITION: During reaming see drill penetrate posteriorly beyond lateral wall into posterior fossa, after reaming pass probe along posterior tunnel wall and probe passes through into posterior space (no resistance). MANAGEMENT: If identified intra-operatively before graft passage, switch to suspensory button fixation (Endobutton, TightRope, RetroButton) which relies on lateral femoral cortex for fixation and does NOT require intact posterior wall (button sits on lateral cortex extra-articularly regardless of posterior wall status). Interference screw femoral fixation contraindicated with posterior wall blowout (screw relies on posterior wall bone for purchase - will fail and pull out if posterior wall absent). Outcome with button fixation equivalent to intact posterior wall if technique proper. EXAM QUESTION: Why is AM portal technique biomechanically and clinically superior to transtibial technique? ANSWER: The AM portal technique allows independent femoral tunnel drilling positioned at anatomic center of AM bundle footprint (10-11 o'clock right knee, posterolateral position on lateral wall) creating oblique graft orientation that better replicates native ACL anatomy and biomechanics. The transtibial technique drills femoral tunnel through tibial tunnel which geometrically constrains femoral tunnel to anterior-vertical position (11-12 o'clock right knee) creating vertical graft with poor restraint to rotational loads especially pivot shift. Multiple Level 1 studies and meta-analyses show AM portal technique provides superior rotational stability (negative pivot shift 90-95 percent versus 70-80 percent transtibial), better IKDC scores, higher patient satisfaction, higher return to sport rates, and lower graft failure rates (5-10 percent versus 10-15 percent) at 5-10 year follow-up. Anatomic graft position more closely restores normal knee kinematics and loading patterns reducing stress on graft and improving longevity.' - Posterior cortex BLOWOUT (most common technical error femoral tunnel drilling) - tunnel placed too posterior (less than 6mm from over-the-top) or over-reaming with aggressive technique or inadequate depth control. Occurs in 5-10 percent of cases even experienced surgeons. RECOGNITION: Arthroscopically see drill penetrate posteriorly beyond lateral wall, probe passes through posterior tunnel wall into posterior fossa without resistance. MANAGEMENT: Use suspensory button fixation instead of interference screw (button doesn't rely on posterior wall, sits on lateral cortex - outcome equivalent if button used properly). If planning interference screw and posterior wall blown out, must switch to button intra-operatively. Not catastrophic complication if recognized and managed appropriately. PREVENTION: Measure 6-7mm anterior to over-the-top before drilling guidewire, use depth stop on reamer, gentle reaming technique. - Femoral tunnel TOO ANTERIOR (replicates transtibial tunnel error) - creates vertical graft from 11-12 o'clock position (right knee) rather than anatomic 10-11 o'clock. CAUSES: AM portal trajectory incorrect (portal placed too medially or too low limiting access to posterior footprint), inadequate hyperflexion (knee not flexed enough preventing posterior access), surgeon error (misidentifying anatomic landmarks). CONSEQUENCE: Continued rotational instability post-operatively (positive pivot shift grade 1-3), vertical graft with poor rotational control, increased stress concentration leading to graft failure over time, patient dissatisfaction, possible revision surgery. PREVENTION: Confirm guidewire position at 10-11 o'clock before reaming (verify 6-7mm from over-the-top measurement), use hyperflexion 110-120 degrees, identify anatomic landmarks carefully (resident's ridge, over-the-top, cartilage margin), test AM portal trajectory with probe before drilling. If anterior tunnel identified before reaming (guidewire malpositioned), remove wire and re-drill correctly. If identified after reaming, may need to abandon tunnel and re-drill new tunnel (or accept if only mildly anterior 1-2mm off) or abort and stage. - SHORT FEMORAL TUNNEL (less than 25mm length) - inadequate fixation especially for suspensory button devices. CAUSES: Small patient (pediatric, petite female), guidewire angled too obliquely from AM portal to lateral cortex creating short tunnel, over-the-back technique. CONSEQUENCE: Button can pull through lateral cortex (inadequate bone thickness less than 25mm for secure button seating), excessive button toggle (motion) causing pain or fixation failure, screw may not achieve adequate purchase if using interference screw. PREVENTION: Measure tunnel length with depth gauge before reaming, aim guidewire more perpendicular to lateral cortex (less oblique angle creates longer tunnel), use outside-in technique with acorn reamer. MANAGEMENT if short tunnel (less than 25mm): Can use interference screw femoral fixation instead of button (screw does not require long tunnel), or use button with understanding of higher failure risk and consider hybrid fixation (button plus screw), or use cross-pin fixation (TransFix) which does not depend on tunnel length. - Articular cartilage damage (tunnel placed too PROXIMAL/SUPERIOR) - femoral tunnel aperture violates inferior edge of weight-bearing articular cartilage. CAUSES: Tunnel positioned less than 2-3mm from cartilage margin, guidewire angled superiorly, inadequate identification of cartilage edge. CONSEQUENCE: Creates iatrogenic chondral defect on lateral femoral condyle (weight-bearing surface), accelerated post-traumatic arthritis, may require secondary cartilage restoration procedure (microfracture, osteochondral autograft, autologous chondrocyte implantation), poor outcomes. PREVENTION: Stay 2-3mm inferior to cartilage margin (identify cartilage edge with probe, mark safe zone), verify wire position before reaming, arthroscopic visualization confirms position before committing. If cartilage damage identified (see exposed bone at tunnel aperture), document and consider treatment based on size (small less than 1cm may observe, larger or weight-bearing may need microfracture at time of ACL or staged). - Lateral femoral condyle FRACTURE (rare but catastrophic) - from excessive notchplasty weakening lateral wall combined with aggressive reaming. CAUSES: Removing greater than 5-7mm bone during notchplasty, thin lateral wall from small patient or anatomy, aggressive reaming technique, osteoporotic bone. INCIDENCE: Less than 1 percent but devastating. PRESENTATION: Visible crack or fracture line on lateral wall intra-operatively, instability of lateral wall when probed, post-operative pain and dysfunction. MANAGEMENT: If identified intra-operatively, may need screw fixation of fracture (percutaneous lateral approach with cannulated screws across fracture), consider aborting ACL reconstruction and staging after fracture heals (6-12 weeks with protected weight-bearing), or proceed cautiously with button fixation avoiding additional stress. PREVENTION: Conservative notchplasty (3-5mm maximum, only if indicated), gentle reaming technique, avoid over-reaming. ### Step 6: Tibial Tunnel Creation - Anatomic Footprint Technique Tibial Tunnel Creation - Anatomic Footprint Technique: GOAL: Create tibial tunnel with intra-articular aperture positioned at CENTER of native ACL tibial footprint for anatomic graft position and optimal biomechanics. TIBIAL FOOTPRINT ANATOMY: Located on tibial plateau posterior to anterior horn of lateral meniscus, anterior and slightly lateral to PCL tibial insertion, medial to lateral tibial spine. In AP dimension: Center of footprint at junction of anterior 43 percent and posterior 57 percent of tibial width (classic teaching says 7mm anterior to PCL insertion). In mediolateral dimension: Centered or slightly lateral (not purely medial). Shape is oval/elliptical oriented anteroposterior. VISUALIZATION: View from AL portal with knee flexed 90 degrees, working instruments through AM portal. Use motorized shaver and radiofrequency ablation to remove soft tissue and clearly visualize footprint (should see exposed bone of tibial plateau). Use arthroscopic ruler or depth gauge to measure from anterior horn of lateral meniscus (reference point) to center of footprint (typically 5-7mm posterior to anterior horn attachment). Can mark center with electrocautery tip creating small divot. GUIDEWIRE PLACEMENT: Use tibial ACL guide (external guide positioned on anterior tibia with intra-articular arm positioned at footprint center). Typical tibial guide angles: 50-55 degrees from horizontal (creates oblique tunnel from anterior tibial cortex to posterior footprint on plateau). More vertical angles (60-70 degrees) create anterior footprint position risking graft impingement and roof blowout (avoid). Flatter angles (40-45 degrees) create posterior footprint position risking PCL injury and posterior cortex blowout (avoid). Ideal 50-55 degrees balances anatomic position with safety. EXTERNAL GUIDE POSITION: Place guide on ANTEROMEDIAL aspect of proximal tibia (NOT anterior midline). Entry point should be 3-4cm distal to joint line (below tibial tubercle apophysis in skeletally immature, at tubercle level in skeletally mature) and medial enough to avoid lateral cortex blowout but not so medial that tunnel too oblique. Mark skin incision site (if not already incised). Incise skin 1.5cm vertical or longitudinal (protect infrapatellar branch of saphenous nerve which crosses anterior tibia obliquely - subcutaneous nerve providing sensation to anterior knee, injury causes numb area but no functional deficit, dissect bluntly to identify and protect). Develop subcutaneous tissues down to periosteum of tibia. Place guide sleeve through incision onto anterior tibial cortex. INTRA-ARTICULAR GUIDE ARM: Pass intra-articular arm of tibial guide through AM portal into joint. Position tip of guide at marked center of tibial footprint (viewing from AL portal). Confirm position: 5-7mm posterior to anterior horn of lateral meniscus, anterior and lateral to PCL, centered on footprint, not impinging on PCL or posterior horn of medial meniscus. Typical footprint center corresponds to "7mm anterior to PCL" measurement on lateral fluoroscopy (though arthroscopic visualization more accurate than fluoroscopy). CRITICAL CHECKPOINT: Verify guide arm position arthroscopically before drilling wire - should be at anatomic footprint center, not too anterior (would cause roof impingement) or too posterior (would risk PCL injury), not too medial or lateral. Can use second spinal needle as marker to compare positions. DRILL GUIDEWIRE: With guide stabilized (assistant holds external guide firmly against anterior tibia, surgeon controls intra-articular arm position), drill 2.4mm smooth guidewire from outside (anterior tibia) toward inside (joint) through guide from anterior tibial cortex through footprint center exiting posteriorly on tibial plateau. Watch wire advance arthroscopically (should emerge exactly at marked footprint center). COMMON ERROR: Wire position migrates medially or laterally during drilling if guide not held firmly (wire skives off bone) - maintain firm pressure on guide throughout drilling. Advance wire fully until tip well beyond posterior cortex of tibia (into soft tissues posteriorly) to prevent wire pullback during reaming. CONFIRM WIRE POSITION arthroscopically: Intra-articular wire exit should be at marked footprint center (5-7mm posterior to anterior horn lateral meniscus, anterior and lateral to PCL, centered mediolaterally). If malpositioned, REMOVE wire and re-drill (do not proceed with malpositioned wire). Can confirm with lateral fluoroscopy (wire should emerge at junction of anterior one-third/posterior two-thirds of tibia or 7mm anterior to posterior tibial cortex). MEASURE TIBIAL TUNNEL LENGTH: Use depth gauge over guidewire measuring from anterior tibial cortex (entry point) to posterior cortex (exit point on tibial plateau). Typical tibial tunnel length 40-50mm depending on patient size and tunnel angle. Record measurement (needed for interference screw length selection - screw should be 5-10mm shorter than tunnel to avoid screw prominence). REAM TIBIAL TUNNEL: Select cannulated reamer matching graft diameter (typically 8-9mm if graft is 8-9mm diameter). Some surgeons ream 0.5mm larger for easier graft passage, others match exactly for tighter fit. Insert cannulated reamer over guidewire from outside (anterior tibia incision) toward inside (joint) using power drill on low speed. Advance reamer slowly with steady pressure watching arthroscopically as reamer emerges at footprint center. Ream to full depth until reamer exits posteriorly on tibial plateau (should see reamer break through into joint at marked footprint). CRITICAL during reaming: Avoid OVER-REAMING - stop once reamer aperture fully emerges at footprint (do not advance further or will enlarge aperture excessively creating keyhole defect). Watch for PCL proximity (reamer should not contact or abrade PCL fibers - if PCL at risk, may need to adjust wire position more anteriorly or laterally). Maintain straight trajectory (do not angle reamer or will create elliptical tunnel). BACK REAMER OUT while still rotating (clears bone chips from tunnel). Remove guidewire. DEBRIS REMOVAL: Use motorized shaver through AM portal to remove bone debris from tibial tunnel aperture and joint. Use suction through anterior tibial incision to clear tunnel of bone chips and blood. Irrigate copiously. TUNNEL MEASUREMENT with dilator: Pass graduated dilator probe through tibial tunnel from outside to inside confirming tunnel diameter (should accept probe matching graft size), measuring tunnel length (40-50mm typical), checking for smooth cylindrical tunnel without sharp edges at aperture that could abrade graft. APERTURE EDGES: Inspect arthroscopically - tibial tunnel aperture should have smooth rounded edges (not sharp bone spicules that would abrade graft fibers causing graft failure over time from repetitive microtrauma). If sharp edges present, use rasp or curette to smooth edges, or use motorized burr to chamfer edges creating beveled transition from tunnel to joint. FINAL CHECK: Pass switching stick or looped suture through tibial tunnel from outside to inside (emerges in joint at footprint center) - will use this to pass graft later. Confirm tibial tunnel position anatomic (center of footprint), adequate length (40-50mm), appropriate diameter (matches graft), smooth aperture (no sharp edges), does not impinge on PCL or menisci, does not communicate with femoral tunnel (separate independent tunnels). Record tibial tunnel parameters (length, diameter, position) in operative note. **Technical Tip**: EXAM KEY: 'TIBIAL TUNNEL POSITION is equally critical as femoral tunnel for achieving anatomic ACL reconstruction and preventing complications. ANATOMIC TIBIAL FOOTPRINT: Native ACL tibial footprint is OVAL/ELLIPTICAL structure oriented anteroposterior measuring approximately 14mm AP dimension by 11mm mediolateral dimension (larger than commonly appreciated). Footprint center located at junction of anterior 43 percent and posterior 57 percent of tibial plateau width (NOT exactly midpoint - slightly posterior to midpoint). Alternative measurement: 7mm ANTERIOR to posterior tibial cortex on lateral fluoroscopy or 7mm anterior to PCL tibial insertion (classic teaching used for decades). Footprint positioned posterior to anterior horn of lateral meniscus (5-7mm posterior to meniscal attachment), anterior and slightly lateral to PCL insertion, medial to lateral tibial spine (spine forms lateral boundary). HISTORICAL TIBIAL TUNNEL ERRORS with transtibial technique: Femoral tunnel drilled through tibial tunnel forcing BOTH tunnels into single trajectory creating geometric compromise. Tibial tunnel often ended up too ANTERIOR on footprint (anterior to anatomic center) to accommodate femoral tunnel trajectory. CONSEQUENCE of anterior tibial tunnel: (1) ROOF IMPINGEMENT (graft rubs on anterior roof of intercondylar notch during terminal extension) causing extension loss (mechanical block preventing full extension 0 degrees), graft abrasion and failure, cyclops lesion formation, quadriceps shutdown from inability to achieve full extension, patellofemoral pain and arthritis. (2) Vertical graft orientation (from anterior tibial tunnel to anterior femoral tunnel creates vertical trajectory) with poor rotational stability and high stress concentration at tunnel apertures. MODERN INDEPENDENT TUNNEL TECHNIQUE: Tibial tunnel drilled independently at anatomic footprint center, femoral tunnel drilled separately through AM portal at anatomic femoral footprint center, creates OBLIQUE graft orientation from posterior femoral footprint to central/slightly posterior tibial footprint replicating native ACL anatomy. TIBIAL TUNNEL ANGLE considerations: SAGITTAL PLANE angle (from horizontal): Ideal 50-55 degrees creates balance between anatomic footprint position and avoiding complications. Too vertical (greater than 60 degrees) forces tibial tunnel anterior on footprint risking roof impingement and anterior tunnel position (non-anatomic). Too horizontal (less than 45 degrees) creates posterior tibial tunnel risking PCL injury during drilling, posterior cortex blowout, technical difficulty with posterior fixation. CORONAL PLANE angle: Slight medial-to-lateral angulation (NOT straight anterior-posterior) - tunnel starts anteromedial on tibial cortex and angles laterally toward lateral aspect of footprint. This accommodates natural anatomy (footprint centered or slightly lateral on tibial plateau) and prevents tunnel too medial. TIBIAL TUNNEL APERTURE EDGES critical concept: Sharp bone edges at intra-articular aperture (where tunnel meets joint) act as knife abrading graft fibers during knee ROM (graft bends over aperture edge repetitively with flexion-extension cycles creating microtrauma to graft fibers). Over months to years this repetitive abrasion causes graft fiber disruption, graft weakening, progressive graft elongation (increased laxity), eventual graft failure (MOST common cause of late ACL graft failure 2-10 years post-operatively - insidious graft attenuation from tunnel edge abrasion rather than acute rupture). PREVENTION: Ensure tibial tunnel aperture has SMOOTH ROUNDED edges (no sharp bone spicules or corners). Use rasp or curette or motorized burr to chamfer edges creating beveled transition zone from tunnel to joint (30-45 degree bevel removes sharp corner distributing stress over larger area). Can also use larger diameter reamer at tunnel aperture only (expand aperture 1mm creating beveled edge). Inspect arthroscopically after reaming (should see smooth rounded edge without sharp corners). CRITICAL RELATIONSHIP BETWEEN TIBIAL TUNNEL and PCL: PCL insertion on tibia is located POSTERIOR and MEDIAL to ACL insertion (2-3mm separation). Tibial tunnel must be positioned ANTERIOR and LATERAL to PCL to avoid injury. If tibial tunnel too far posterior or too medial, risks direct PCL injury during reaming (reamer can lacerate or partially transect PCL fibers) or close proximity causing graft-PCL impingement (ACL graft rubs on PCL during knee motion causing graft or PCL abrasion). EXAM SCENARIO: Post-operatively your ACL reconstruction patient has positive posterior drawer and increased posterior tibial translation on stress radiographs. What happened? ANSWER: This suggests iatrogenic PCL injury from tibial tunnel drilling (tunnel positioned too posterior or medial causing reamer to damage PCL during tunnel creation). Management depends on severity: Partial PCL injury (less than 50 percent fibers, stable on exam, less than 5mm side-to-side difference) can be managed conservatively with bracing and quadriceps strengthening allowing PCL healing over 12 weeks. Complete PCL disruption (greater than 50 percent fibers, unstable on exam, greater than 10mm side-to-side difference) requires surgical repair or reconstruction (may need staged after ACL graft heals or can address acutely if recognized intra-operatively). Prevention involves careful tibial tunnel positioning anterior and lateral to PCL, arthroscopic visualization of PCL during tibial reaming (watch PCL does not move or deform suggesting contact), stopping reaming if PCL proximity concerning. TIBIAL TUNNEL LENGTH considerations: Typical 40-50mm from anterior cortex entry to posterior cortex exit (varies with patient size and tunnel angle). IMPORTANCE: Adequate tunnel length needed for interference screw fixation (screw should be 5-10mm shorter than tunnel to prevent screw prominence beyond posterior cortex which can irritate soft tissues or violate posterior structures). If tunnel too short (less than 30mm from small patient), may have difficulty achieving adequate screw purchase (need minimum 20-25mm screw length for secure fixation). If planning adjustable-loop button tibial fixation (TightRope, Zip-Loop), tunnel length less critical as button sits on anterior tibia extra-articularly and length does not affect fixation security. FLUOROSCOPY versus ARTHROSCOPY for tibial tunnel positioning: Historic approach relied heavily on lateral fluoroscopy imaging to confirm tibial tunnel position (looking for 7mm anterior to posterior tibial cortex). MODERN approach: Direct ARTHROSCOPIC VISUALIZATION superior to fluoroscopy for tunnel positioning (can see actual footprint anatomy, identify menisci and PCL directly, confirm tunnel emerges at anatomic center). Fluoroscopy used as adjunct for confirmation but not primary guidance. Studies show arthroscopic-guided tunnel placement more accurate and reproducible than fluoroscopy-guided (fluoroscopy has projection errors and anatomic variation making 7mm rule imprecise).' - PCL INJURY from tibial tunnel too posterior or too medial (1-5 percent incidence) - reamer contacts or lacerates PCL fibers during tunnel drilling. RECOGNITION: Arthroscopically see PCL deform or move during reaming (should remain stationary if adequate clearance), see blood or fiber disruption on PCL surface after reaming, post-operative posterior drawer positive suggesting PCL injury. PREVENTION: Position tibial tunnel 5-7mm ANTERIOR to PCL insertion, view PCL during reaming from AL portal watching for any movement (stop if PCL deforms), use arthroscopic visualization rather than relying solely on fluoroscopy. MANAGEMENT: If partial PCL injury identified (less than 50 percent fibers, stable exam, less than 5mm side-to-side difference on stress X-ray), can manage conservatively with quadriceps bracing for 12 weeks allowing healing. If complete PCL disruption (unstable exam, greater than 10mm side-to-side difference), may need surgical repair or reconstruction (can be staged after ACL heals or addressed acutely if recognized intra-operatively). - ROOF IMPINGEMENT from tibial tunnel too ANTERIOR (high incidence 10-20 percent if technique poor) - tunnel positioned anterior to anatomic footprint center creates anterior vertical graft that impinges on anterior roof of intercondylar notch during terminal extension. CONSEQUENCE: Extension loss (cannot achieve 0 degrees extension - typically 5-10 degrees flexion contracture), cyclops lesion formation (fibrous nodule from impingement), graft abrasion and failure, quadriceps shutdown, patellofemoral pain and arthritis. RECOGNITION: Intra-operatively during final ROM check see graft contact anterior roof (view from AL portal, bring knee to full extension, graft should not touch roof or lateral wall - if contacts need to address). Post-operatively patient has extension loss starting immediately or within 6 weeks, clicking sensation, quadriceps weakness. MRI shows soft tissue nodule anterior to graft (cyclops lesion). PREVENTION: Position tibial tunnel at anatomic footprint center (NOT too anterior), use adequate tunnel angle (50-55 degrees NOT too vertical greater than 60 degrees), perform notchplasty if narrow notch or impingement risk, confirm full extension 0 degrees before leaving OR (non-negotiable checkpoint - never accept extension loss at end of case). MANAGEMENT: If identified intra-operatively before closing, perform notchplasty to clear impingement (remove bone from anterior roof or lateral wall creating clearance). If identified post-operatively, arthroscopic debridement of cyclops lesion and notchplasty typically restores extension immediately (good outcomes if addressed early). - POSTERIOR CORTEX BLOWOUT from tibial tunnel too posterior (less common 1-3 percent) - tunnel exits posterior to tibial footprint onto posterior slope of tibia. CONSEQUENCE: Inadequate bone for tibial interference screw fixation (screw needs solid bone anteriorly and posteriorly, blowout eliminates posterior wall), risk to popliteal neurovascular structures posteriorly (vessels and nerves located just posterior to tibia separated only by thin posterior capsule). RECOGNITION: During reaming see reamer exit too far posterior (beyond footprint onto posterior slope), probe or depth gauge measures short tunnel (less than 30mm suggesting early posterior exit), feel soft tissue rather than bone at posterior tunnel wall. MANAGEMENT: If identified before graft passage, switch to suspensory button tibial fixation or backup tibial fixation (all-inside technique with socket instead of tunnel, hybrid fixation with screw plus button, post screw). Do NOT use standard interference screw with posterior blowout (will fail from inadequate purchase). PREVENTION: Position tunnel at anatomic footprint (NOT too posterior), use 50-55 degree tunnel angle (NOT too horizontal less than 45 degrees), arthroscopic visualization of tunnel emergence at footprint center. - LATERAL CORTEX BLOWOUT from tibial tunnel angled too laterally (1-2 percent) - tunnel exits lateral tibial cortex creating large defect. CONSEQUENCE: Inadequate bone for tunnel or fixation (large lateral defect weakens tibia structurally), graft prominence on lateral tibia causing irritation or pain, cosmetic deformity (visible or palpable tunnel on lateral leg). RECOGNITION: Palpate lateral tibia during or after drilling (feel defect or crepitus), visualize lateral cortex arthroscopically or fluoroscopically (see tunnel communicate with lateral cortex), probe passes laterally through defect. MANAGEMENT: If small blowout (less than 5mm), may proceed cautiously with interference screw fixation angled away from defect or use button fixation. If large blowout (greater than 5mm), abort and stage procedure after defect heals (bone graft defect, allow 8-12 weeks healing, redo ACL reconstruction with corrected tunnel position). PREVENTION: Position tibial tunnel with slight medial-to-lateral angulation (NOT excessive lateral angulation), use external guide on anteromedial tibia (NOT anterior midline or anterolateral), confirm tunnel trajectory before drilling with guidewire, fluoroscopic confirmation if uncertain. - Saphenous nerve or infrapatellar branch injury from anterior tibial incision (common 20-30 percent have numbness, usually not clinically significant) - nerve crosses anterior tibia obliquely in subcutaneous plane, injured during skin incision or subcutaneous dissection. CONSEQUENCE: Numbness on anterior knee/proximal medial leg (area of sensation loss variable), hyperesthesia or dysesthesia (hypersensitivity or unpleasant sensation), painful neuroma formation (rare less than 5 percent). No motor function loss (pure sensory nerve). PREVENTION: Incise skin sharply in line with nerve trajectory (oblique or vertical incision), dissect bluntly in subcutaneous plane (spread with hemostat rather than cutting), identify and protect nerve if visualized during dissection (retract gently). Minimize incision length (1.5cm adequate). MANAGEMENT: If injury occurs (numbness noted post-operatively), counsel patient that sensation usually recovers partially over 6-12 months (70-80 percent improve), symptoms rarely bothersome long-term. If painful neuroma develops, may need neuroma excision or nerve transection and burial in muscle (rare indication less than 1-2 percent). ### Step 7: Graft Passage into Joint Graft Passage into Joint: GOAL: Pass prepared hamstring graft through tibial tunnel into joint and subsequently through femoral tunnel for fixation without damaging graft or introducing infection. TIMING: Perform graft passage after BOTH tunnels created (femoral and tibial) and measured. PREPARATION: Have graft ready on back table in moist sponge soaked with saline or antibiotic solution (keep graft hydrated throughout - do NOT allow graft to dry which weakens collagen fibers). Ensure sutures secure at both ends (typically 5-6 whipstitches creating 15-20mm suture-tendon interface preventing suture pullout), measure final graft length with sutures (record in operative note). PASSING SUTURE PLACEMENT: Thread passing suture (typically No. 2 or No. 5 braided non-absorbable suture or heavy silk suture or thick looped suture) through tibial tunnel from OUTSIDE (anterior tibia) to INSIDE (joint) using long suture passer or looped wire or passing rod. Watch arthroscopically as passing suture emerges from tibial tunnel aperture into joint. Pull passing suture fully through until suture exits anteriorly through anterior tibial incision (now have passing suture loop extending from tibial incision through tunnel into joint). GRAFT ATTACHMENT TO PASSING SUTURE: Remove graft from sterile field maintaining sterility. Attach FEMORAL END of graft (end with femoral fixation device - typically suspensory button already attached with adjustable loop or fixed loop, or end intended for femoral tunnel if using interference screw) to passing suture. Use square knot or surgeon's knot securely tying graft sutures to passing suture (ensure knot will not come loose during passage). Alternative: If using button fixation, button suture loops serve as passing suture (no separate passing suture needed - pull button loops to pass graft). GRAFT PASSAGE TECHNIQUE: Assistant or surgeon slowly pulls passing suture from anterior tibial incision (outside) while second surgeon feeds graft into tibial tunnel from back table and monitors arthroscopically. CRITICAL: Graft must pass smoothly through tunnel without twisting, bunching, or catching on tunnel edges. Watch arthroscopically as graft emerges from tibial tunnel aperture into joint (should see graft advance steadily without resistance). If graft catches or bunches (common at tunnel aperture if edges sharp), STOP pulling - may need to release tension, smooth tunnel edges with rasp or curette, re-attempt passage. Continue pulling until entire graft length passes through tibial tunnel into joint with femoral end of graft positioned intra-articularly (ready for femoral tunnel passage). CONFIRM GRAFT ORIENTATION: Ensure graft not twisted 180 degrees or 360 degrees (twisted graft weakens biomechanical properties reducing ultimate failure load by 20-30 percent and creates abnormal stress distribution leading to accelerated failure). Arthroscopically visualize graft in joint (should be smooth and uniform without visible twisting - can see suture pattern should be consistent). If twisted, pull graft back out and re-pass correctly oriented. NEXT STEP PREPARATION: Position femoral end of graft at entrance of femoral tunnel (use probe or grasper through AM portal to guide graft toward femoral tunnel opening on lateral wall of intercondylar notch). For BUTTON FIXATION: Pass button and suture loops through femoral tunnel first (button will deploy on lateral femoral cortex extra-articularly), then pull graft up into tunnel. For INTERFERENCE SCREW femoral fixation: Pass graft directly into femoral tunnel, advance graft to full depth, then insert screw alongside graft. **Technical Tip**: EXAM KEY: 'GRAFT PASSAGE is deceptively simple step but critical errors here can compromise entire reconstruction. GRAFT TWISTING is common technical error (reported incidence 5-15 percent even experienced surgeons) - occurs when graft rotates 180 degrees or 360 degrees around long axis during passage through tibial tunnel into joint. CAUSES: Graft bunches and rolls during passage through tunnel (especially if tunnel edges sharp or diameter too tight), passing suture twists during pulling, inadequate attention to graft orientation on back table before passage. BIOMECHANICAL CONSEQUENCES: Twisted graft has 20-30 percent REDUCTION in ultimate tensile strength (failure load) compared to untwisted graft (published biomechanical studies show twisted hamstring constructs fail at 2000-2500N versus 3000-3500N for untwisted - significant strength loss). Twisting also creates abnormal stress distribution within graft (fibers loaded unevenly causing some fibers to fail prematurely while others underloaded), accelerates graft failure from repetitive loading (fibers abrading against each other at twist points causing microtrauma and weakening). CLINICAL OUTCOME: Twisted grafts have HIGHER failure rates (15-20 percent versus 5-10 percent for untwisted grafts at 5 years in some studies), earlier failure (median time to failure 18-24 months versus 36-48 months), lower functional scores. RECOGNITION OF TWISTING: INTRA-OPERATIVELY arthroscopic visualization shows graft appears to spiral or twist around long axis (suture pattern should run parallel to graft fibers in straight lines - if sutures spiral around graft indicates twisting). Can also assess tension on graft (twisted graft often looser than expected suggesting length lost to twisting). PREVENTION: (1) Mark graft orientation on back table before passage (use marking pen to draw line along length of graft indicating anatomic orientation - line should remain straight after passage confirming no twisting). (2) Careful graft passage (pull slowly watching arthroscopically for smooth advancement, if bunching occurs stop and reassess). (3) Smooth tunnel edges (chamfer sharp corners at tibial and femoral tunnel apertures so graft glides without catching). (4) Adequate tunnel diameter (undersized tunnel forces graft compression causing bunching and twisting - tunnel should be same diameter as graft or 0.5mm larger allowing smooth passage). MANAGEMENT IF IDENTIFIED: If twisting recognized before fixation, pull graft back out completely and re-pass correctly oriented (time-consuming but necessary for optimal outcome - do not accept twisted graft "close enough"). If identified after fixation, may need revision surgery (no way to untwist graft once fixed at both ends). GRAFT LENGTH VERIFICATION during passage: As graft passes through tibial tunnel into joint, verify sufficient graft length to span from tibial fixation point through tibial tunnel through joint space into femoral tunnel to femoral fixation point. TYPICAL graft length needed: 70-90mm total (tibial tunnel 40-50mm, intra-articular span 10-20mm, femoral tunnel 30-35mm plus fixation device length). If graft too short (insufficient length measured less than 70mm), cannot achieve proper tunnel fill or fixation and may need to revise graft harvest (take more length of tendons) or consider allograft augmentation or abort and use different graft source. GRAFT HYDRATION critical throughout: Graft must remain MOIST during entire procedure (from harvest through passage through fixation). Dry collagen loses tensile strength (hydrated collagen has organized fibril structure with water molecules providing lubrication between fibrils allowing sliding without friction - dehydrated collagen has fibrils adhering together with increased friction causing microtrauma during loading). Keep graft on MOIST SPONGE soaked with saline or antibiotic solution (common antibiotic soak: bacitracin 50,000 units in 500mL saline), re-moisten every 10-15 minutes during preparation, minimize graft exposure time on dry surfaces. Studies show dehydrated grafts have 15-25 percent reduction in failure load compared to hydrated grafts. ANTIBIOTIC SOAKING of graft (pre-passage): Common practice to soak graft in antibiotic solution for 5-10 minutes before passage (theoretically reduces infection risk by pre-treating graft with antibiotics that elute into surrounding tissues post-operatively). Typical antibiotics used: Bacitracin (50,000 units in 500mL saline), vancomycin (1 gram in 500mL saline), or cefazolin (1 gram in 500mL saline). EVIDENCE: No high-quality RCTs proving benefit but widespread practice based on logical rationale (graft is avascular until remodeling occurs over weeks to months making graft vulnerable to bacterial colonization - pre-soaking provides local antibiotic delivery). No evidence of harm from soaking (antibiotics do not weaken graft or impair healing). EXAM QUESTION: What are biomechanical consequences of graft twisting and how do you prevent it? ANSWER: Graft twisting (180-360 degree rotation around long axis) reduces ultimate tensile strength by 20-30 percent (failure load decreases from 3000-3500N to 2000-2500N for hamstring grafts), creates abnormal stress distribution causing uneven fiber loading and early failure of individual fascicles, increases friction between fibers at twist points leading to accelerated graft degradation from repetitive loading, and clinically results in higher failure rates (15-20 percent versus 5-10 percent at 5 years). Prevention involves: (1) Marking graft orientation on back table before passage with line along length that should remain straight indicating no twisting, (2) Ensuring smooth tunnel aperture edges without sharp corners allowing graft to glide through without catching and bunching, (3) Using adequate tunnel diameter matching graft size or 0.5mm larger preventing forced compression during passage, (4) Pulling graft slowly during passage while watching arthroscopically for smooth advancement and stopping if bunching occurs. If twisting identified before fixation, graft should be pulled back out and re-passed correctly oriented even though time-consuming (do not accept twisted graft as compromises reconstruction outcome).' - GRAFT CONTAMINATION from break in sterile technique - graft drops on floor, contacts non-sterile surface, touched with contaminated glove, exposed to environment during passage. CONSEQUENCE: Introduces bacteria to graft causing post-operative infection (septic arthritis or graft infection rate 0.5-2 percent if contaminated, devastating complication requiring graft removal, debridement, prolonged antibiotics, possible staged revision). PREVENTION: Maintain strict sterile technique throughout graft handling (keep graft on sterile back table until passage, use sterile instruments for graft manipulation, avoid touching graft with contaminated surfaces, minimize personnel traffic near sterile field). If contamination suspected (graft contacts questionable surface), consider re-sterilizing graft (soak in antibiotic solution for extended time 10-15 minutes) or discarding graft and using allograft or different autograft source. Do NOT proceed with obviously contaminated graft. - GRAFT DAMAGE from sharp tunnel edges - graft fibers lacerated or abraded by sharp bone spicules at tibial or femoral tunnel apertures during passage. CONSEQUENCE: Weakens graft structural integrity (reduced failure load), creates stress concentration at damage site (fibers fail progressively from damaged area), accelerates graft failure from repetitive loading (damaged fibers more vulnerable to propagation of failure). PREVENTION: Smooth ALL tunnel aperture edges before graft passage using rasp or curette or motorized burr creating beveled chamfered edges (30-45 degree bevel distributing stress over larger area), inspect edges arthroscopically before passage (should see smooth rounded transition not sharp corners), pull graft slowly during passage watching for snagging (if catches stop immediately and smooth edge further). RECOGNITION: During passage graft catches or bunches at tunnel aperture (should advance smoothly without resistance), after passage see frayed or damaged fibers on graft surface arthroscopically. If significant damage identified (greater than 25-50 percent of graft cross-section compromised), may need to discard graft and use alternative (allograft or different autograft). - Graft PULLOUT OF SUTURES (graft-suture interface failure) during passage - occurs if sutures not adequate or whipstitch length insufficient or pulling tension excessive. CONSEQUENCE: Graft separates from fixation device or passing suture (cannot pass graft or cannot fix graft if separation at fixation end), need to re-suture graft (time-consuming, may weaken graft further from additional needle passes), may need to harvest new graft if re-suturing not feasible. PREVENTION: Use adequate whipstitch length (minimum 15-20mm of suture-tendon interface, some surgeons use 25mm for extra security), use appropriate suture size (No. 2 braided non-absorbable typical for hamstrings), perform minimum 5-6 locking whipstitches creating secure interface, test graft-suture interface integrity on back table before passage (pull with moderate force confirming no slippage), during passage pull with steady moderate force (avoid excessive jerking or high tension that could disrupt sutures). If pullout occurs, re-suture with longer whipstitch and re-test before re-attempting passage. - GRAFT TOO SHORT after passage - realize graft length insufficient to span from tibial fixation to femoral fixation after graft already in tunnels. CONSEQUENCE: Cannot achieve adequate tunnel fill (graft does not reach full depth of femoral tunnel leaving gap which weakens fixation and increases failure risk), cannot use planned fixation device (button may not reach lateral cortex, screw has inadequate graft length to engage), graft under excessive tension (if forced to span inadequate length increases stress and failure risk). PREVENTION: Measure graft carefully on back table BEFORE passage (typical need 70-90mm total length minimum), measure tunnel lengths and calculate required graft length (tibial tunnel length 40-50mm plus intra-articular span 10-20mm plus femoral tunnel length 30-35mm plus fixation device requirements), if graft marginal length (70-75mm borderline), consider taking more tendon length during harvest or using different graft configuration (4-strand versus 3-strand to maintain strength with shorter length). MANAGEMENT if identified after passage: If graft critically short (cannot reach femoral tunnel), may need to abort and harvest contralateral graft or use allograft. If graft marginally short (reaches femoral tunnel but minimal extra length), can modify fixation strategy (use shorter interference screw, use button with shorter loop length, accept slight undertunneling). ### Step 8: Femoral Fixation Femoral Fixation: GOAL: Securely fix femoral end of graft in femoral tunnel with fixation strong enough to allow early rehabilitation without fixation failure or graft pullout during healing phase (minimum 6-12 weeks until graft-bone healing provides biological fixation). TWO main femoral fixation methods: (1) SUSPENSORY BUTTON FIXATION (Endobutton, TightRope, RetroButton) - current most common method 60-70 percent of surgeons. (2) INTERFERENCE SCREW fixation (bioabsorbable or metal screw inserted alongside graft in tunnel). BUTTON FIXATION TECHNIQUE (if using button): Graft attached to button with adjustable loop or fixed loop suture construct on back table during preparation. Button already connected to graft femoral end. PASS BUTTON through femoral tunnel: Use button passing pin or suture to pull button and graft together from joint (intra-articular position) through femoral tunnel toward lateral femoral cortex (extra-articular position). Watch arthroscopically and palpate lateral thigh as button advances (can feel button traverse tunnel). Continue pulling until button fully exits femoral tunnel onto lateral femoral cortex. FLIP BUTTON: Once button clears tunnel, button designed to flip 90 degrees lying flat against lateral cortex (continuous outline button design like Endobutton flips automatically when tensioned, adjustable loop buttons like TightRope require specific flipping maneuver). Confirm button flip: (1) Arthroscopically - should see graft advance into femoral tunnel as button seats on cortex, (2) Palpate lateral thigh - feel button lying flat against cortex (distinct hard edge under skin), (3) Fluoroscopy - lateral view shows button parallel to femoral shaft on lateral cortex. TENSION GRAFT: Pull on tibial end of graft from anterior tibia while cycling knee through ROM (flexion-extension 0-120 degrees repeated 20-30 cycles) to tension graft and remove slack from fixation construct. Tensioning important for adjustable loop buttons (loop tightens as graft pulled reducing loop length and seating graft firmly in tunnel). Fixed loop buttons already at set length. FINAL SEATING: Ensure button flat against lateral cortex with graft pulled to appropriate tension (typically 20-30 pounds tension or moderate pull). Knee flexed to 20-30 degrees during tibial fixation (some surgeons prefer full extension 0 degrees or 15 degrees - controversy regarding optimal knee angle, generally 15-30 degrees flexion accepted). Button fixation ADVANTAGES: Does not require intact posterior femoral cortex (works even with posterior wall blowout), provides very strong fixation (typically 800-1200N pullout strength exceeding native ACL strength), allows graft length adjustment with adjustable loop (can modify graft position by pulling to change loop length), less risk of graft laceration compared to interference screw (no screw threads cutting fibers). DISADVANTAGES: Button prominence on lateral thigh (10-20 percent patients feel button under skin, rarely painful or bothersome), theoretical concern for graft toggle or windshield wiper effect (graft motion within tunnel before graft-bone healing - may enlarge tunnel though clinical significance debated), higher cost than interference screw. INTERFERENCE SCREW FEMORAL FIXATION TECHNIQUE (alternative to button): Graft passed into femoral tunnel to full depth (usually leaving 5mm of graft extending beyond tunnel into joint for later tensioning). Select interference screw size: Diameter should be SAME as tunnel diameter (8mm tunnel uses 8mm screw, 9mm tunnel uses 9mm screw), or 1mm larger (9mm screw in 8mm tunnel - not commonly used as risks damaging graft from compression). Length should be 5-10mm SHORTER than tunnel length (femoral tunnel 30mm uses 20-25mm screw - shorter screw prevents screw prominence beyond lateral cortex and reduces risk of screw diverging into joint or out posterior cortex). Material: Bioabsorbable (PLLA, PLGA copolymers) most common current practice (gradual resorption over 12-24 months replaced by bone, eliminates hardware, avoids interference with future surgery like revision or TKA), metal (titanium) alternative (stronger pullout but permanent, can interfere with MRI imaging artifact, may complicate revision surgery if needed years later). SCREW INSERTION: Insert cannulated screw over guidewire OR use non-cannulated screw with self-drilling/self-tapping design. Position screw ALONGSIDE graft (not through graft center which would lacerate fibers). Use screw driver to advance screw into femoral tunnel parallel to graft and tunnel axis. CRITICAL: Screw should compress graft against tunnel wall (wedging graft between screw threads and bone creating friction fixation). Advance screw to depth where screw head sits flush with lateral femoral cortex or slightly recessed (not prominent which could irritate soft tissues or cause pain). Typical depth: Insert until resistance increases indicating screw fully seated (do not over-tighten which can strip screw or break screw especially bioabsorbable screws which weaker than metal). SCREW FIXATION ADVANTAGES: Lower cost than button, avoids prominence on lateral cortex (screw head recessed), may provide better graft-bone healing (compression at graft-bone interface enhances healing though evidence mixed). DISADVANTAGES: Requires intact posterior femoral cortex (posterior wall blowout contraindication for interference screw as screw relies on posterior wall for purchase), risk of graft laceration from screw threads (can weaken graft by cutting fibers if screw malpositioned through graft center or over-advanced), bioabsorbable screws can break during insertion (brittle material fractures if excessive torque 5-15 percent breakage rate, usually not clinically significant), screw divergence (screw does not follow tunnel axis and exits posteriorly or into joint - serious complication requiring screw removal and re-fixation). CONFIRM FEMORAL FIXATION SECURITY: Test fixation by pulling on tibial end of graft with moderate force (20-30 pounds tension) - graft should not pull out of femoral tunnel or show excessive motion. Cycle knee through ROM 20-30 times (0-120 degrees flexion-extension) to remove slack and pre-condition graft. Arthroscopically visualize femoral tunnel aperture (should see graft filling tunnel without gaps, no graft pullout or toggle with ROM). FINAL CHECKPOINT before tibial fixation: Femoral fixation secure (button flipped on lateral cortex or interference screw seated at appropriate depth), graft tensioned appropriately (no slack in construct), knee can achieve full ROM (0 degrees extension to 130 degrees flexion without graft over-constraint or impingement), graft positioned anatomically in femoral tunnel (centered at AM bundle footprint 10-11 o'clock). **Technical Tip**: EXAM KEY: 'FEMORAL FIXATION METHODS represent significant evolution in ACL surgery over past 20 years with ongoing debate regarding optimal technique. THREE main categories: (1) SUSPENSORY BUTTON fixation (Endobutton, TightRope, RetroButton - graft suspended from button sitting on lateral femoral cortex extra-articularly), (2) INTERFERENCE SCREW fixation (bioabsorbable or metal screw wedging graft against tunnel wall intra-tunnel fixation), (3) HYBRID FIXATION (combination of button and screw providing dual fixation points - backup fixation if one method fails). BIOMECHANICAL PROPERTIES comparison: SUSPENSORY BUTTON fixation provides highest pullout strength (800-1200N typical for modern button devices with adjustable loops, exceeds native ACL failure load of 2000N when considering entire graft not just fixation), fixation strength independent of bone quality (relies on cortical bone of lateral femur which dense and strong even in osteoporotic patients), fixation strength immediate (full strength from moment of button deployment no need to wait for healing). INTERFERENCE SCREW fixation provides moderate pullout strength (400-800N typical for 7-9mm diameter screws depending on bone quality, screw size, thread design), fixation strength dependent on bone quality (cancellous bone of femoral tunnel provides purchase - osteoporosis or poor bone reduces screw holding strength by 30-50 percent), fixation strength immediate from friction but enhances over time with graft-bone healing. HYBRID FIXATION provides highest overall strength (button plus screw 1000-1500N combined) but added complexity and cost without proven clinical benefit (no RCTs showing hybrid superior to button alone for clinical outcomes). CLINICAL OUTCOMES comparison: Multiple Level 1 RCTs and meta-analyses comparing button versus screw femoral fixation show NO significant difference in clinical outcomes (IKDC scores, graft failure rates, return to sport, patient satisfaction all equivalent between groups). One meta-analysis of 15 RCTs including 1,800 patients found no difference in any outcome measure at 2-year follow-up. CONCLUSION: Both button and screw provide adequate fixation when technique proper - choice based on surgeon preference, specific case factors (posterior wall integrity, bone quality, cost), and fixation device availability. SUSPENSORY BUTTON SPECIFIC ISSUES: (1) BUTTON PROMINENCE - 10-20 percent patients report feeling button on lateral thigh (hard lump palpable subcutaneously), rarely painful or functionally limiting (less than 2-3 percent request button removal for pain or irritation), no proven association with worse outcomes. If bothersome, button can be removed after graft-bone healing (minimum 6-12 months post-op) through small lateral incision. (2) BUTTON FLIP FAILURE - button does not flip 90 degrees and remains oriented longitudinally in tunnel rather than transversely on cortex. CAUSES: Inadequate pull on button to flip mechanism, button catching on bone edge at tunnel exit, button design flaw. RECOGNITION: Palpate lateral thigh (button oriented longitudinally feels like linear ridge rather than flat edge), fluoroscopy shows button parallel to tunnel not perpendicular, arthroscopy shows excessive graft motion or graft pulling back suggesting button not seated. CONSEQUENCE: Reduced fixation strength (button may pull through tunnel if not flipped properly), possible fixation failure. MANAGEMENT: If identified intra-operatively, remove button and re-pass (may need to enlarge tunnel slightly or smooth lateral cortex edge), consider switching to interference screw if re-flip unsuccessful. (3) GRAFT-TUNNEL MOTION (windshield wiper effect) - theoretical concern that graft suspended from button allows motion within femoral tunnel during knee ROM before graft-bone healing occurs (graft slides back and forth abrading tunnel walls and potentially enlarging tunnel). EVIDENCE: Motion does occur on imaging studies (CT or MRI show tunnel widening 1-3mm at 6-12 months with button fixation), but clinical significance controversial (RCTs show no difference in outcomes despite tunnel widening, widening stabilizes after graft healing, enlarged tunnels do not correlate with laxity or failure). Current consensus: Tunnel widening radiographic finding of uncertain clinical significance not contraindication to button use. INTERFERENCE SCREW SPECIFIC ISSUES: (1) SCREW DIVERGENCE - screw does not follow tunnel axis and exits through posterior cortex or into joint. CAUSES: Screw starts off-axis during insertion (not aligned with tunnel), soft cancellous bone allows screw to wander, excessive insertion force. INCIDENCE: 5-15 percent of interference screw fixations have some degree of screw divergence. RECOGNITION: Arthroscopically see screw tip penetrate into joint through posterior tunnel wall (visible metal or bioabsorbable screw tip emerging), resistance decreases suddenly during screw insertion (indicates screw penetrated cortex), post-operative CT shows screw position outside tunnel. CONSEQUENCE: If screw penetrates joint posteriorly can damage PCL (screw lacerates PCL fibers causing iatrogenic PCL injury), if penetrates lateral cortex can cause lateral pain or soft tissue irritation, loss of fixation strength (screw threads not engaging tunnel bone). MANAGEMENT: If identified during insertion (feel screw diverge or see tip enter joint), remove screw immediately and re-insert with correct trajectory or switch to button fixation. If identified post-operatively and asymptomatic, can observe. If symptomatic (pain, instability, PCL injury), may need screw removal and possible revision fixation. (2) BIOABSORBABLE SCREW BREAKAGE - screw fractures during insertion from excessive torque. INCIDENCE: 5-15 percent of bioabsorbable screw insertions have screw breakage (brittle PLLA polymer cannot withstand high torque unlike ductile metal screws). RECOGNITION: Feel crack or sudden loss of resistance during screw insertion, see broken screw fragment in tunnel or on screw driver. CONSEQUENCE: Usually not clinically significant if broken screw still provides some fixation (fragment wedged in tunnel), but if fragment loose or fixation inadequate may need removal and re-fixation with new screw or button. MANAGEMENT: If breakage occurs with adequate remaining screw length in tunnel (greater than 15mm) providing fixation, can leave and supplement with backup tibial fixation (augmentation). If inadequate fixation, remove broken screw fragments and insert new screw or convert to button fixation. PREVENTION: Use screw inserter with controlled torque (not excessive force), pre-tap tunnel if bone very dense (creates pilot path reducing insertion resistance), avoid over-tightening. (3) GRAFT LACERATION from screw threads - screw cuts or frays graft fibers during insertion. CAUSES: Screw inserted through center of graft rather than alongside graft, excessive screw diameter (oversized screw compresses and cuts graft), sharp screw threads. CONSEQUENCE: Weakens graft structural integrity (each fiber cut reduces overall graft strength proportionally), creates stress concentration (damaged area fails first under loading), increases failure risk especially early post-op before healing. PREVENTION: Position screw ALONGSIDE graft not through center (screw should be eccentric in tunnel wedging graft against opposite wall), use appropriate screw diameter (same as tunnel or at most 1mm larger), visualize screw position arthroscopically during insertion (should see graft separate from screw path). If significant graft damage observed (greater than 25-50 percent fibers cut), consider removing screw and using button fixation or supplemental tibial fixation to compensate. EXAM QUESTION: Compare biomechanical and clinical outcomes of suspensory button versus interference screw femoral fixation for ACL reconstruction. ANSWER: Suspensory button fixation provides higher ultimate pullout strength (800-1200N versus 400-800N for screw), fixation independent of bone quality (cortical bone always strong versus screw depending on cancellous bone density), and immediate full-strength fixation. Interference screw fixation provides adequate strength for rehabilitation, direct compression enhancing graft-bone healing potentially, and avoids lateral prominence. However, multiple Level 1 RCTs and meta-analyses show NO significant difference in clinical outcomes (IKDC scores, graft failure rates, return to sport, patient satisfaction all equivalent at 2-5 year follow-up). Button fixation associated with radiographic tunnel widening (1-3mm at 6-12 months from graft motion) but no clinical significance. Screw fixation risks divergence (5-15 percent), breakage of bioabsorbable screws (5-15 percent), and graft laceration from threads. Button fixation requires intact lateral cortex (always present) while screw fixation requires intact posterior femoral cortex (blowout in 5-10 percent contraindicating screw). Both methods provide adequate fixation when technique appropriate - choice based on surgeon preference and specific case factors rather than outcome superiority of either method.' - BUTTON FLIP FAILURE - button does not flip and orient transversely on lateral femoral cortex (remains longitudinally in tunnel). CONSEQUENCE: Inadequate fixation strength (button may pull through tunnel if not properly flipped and seated), possible acute fixation failure (graft pulls out of femoral tunnel during rehabilitation or early post-op period), need for revision surgery. RECOGNITION: Palpate lateral thigh feeling for button orientation (should feel flat transverse edge indicating flip, longitudinal ridge suggests no flip), fluoroscopy shows button parallel to tunnel not perpendicular to cortex, arthroscopically see excessive graft motion in femoral tunnel when tensioning. MANAGEMENT: If identified intra-operatively before tibial fixation, pull button back out of femoral tunnel and re-pass attempting flip again (may need to pull harder on button sutures to activate flip mechanism, or smooth lateral cortex edge if bone edge preventing flip, or abandon and use different button or switch to screw fixation). Do not proceed with tibial fixation if button flip questionable. PREVENTION: Pull button firmly until feel distinct flip (tactile feedback through sutures), confirm flip with palpation and fluoroscopy before tensioning, use modern button designs with reliable flip mechanisms (continuous outline designs like Endobutton CL very reliable, older non-continuous buttons higher flip failure rate 5-10 percent). - SCREW DIVERGENCE into joint or through posterior cortex - screw does not follow tunnel trajectory and penetrates posteriorly or laterally. CONSEQUENCE: If penetrates posterior cortex into joint can damage PCL (screw lacerates PCL fibers causing iatrogenic PCL injury with post-operative posterior instability), if penetrates lateral cortex can cause lateral thigh pain or soft tissue irritation, fixation failure (screw threads not engaging tunnel bone providing inadequate purchase), graft damage (screw cuts graft fibers during aberrant trajectory). RECOGNITION during insertion: Resistance suddenly decreases indicating screw penetrated cortex, arthroscopically visualize screw tip emerge through posterior femoral tunnel wall into joint (see metal or bioabsorbable screw tip where should not be visible), inability to advance screw to planned depth (screw stops short suggesting divergence). MANAGEMENT: If identified during insertion (feel or see divergence), STOP immediately and remove screw before fully inserted (partial screw easier to remove than fully seated screw), re-insert new screw with corrected trajectory ensuring screw aligned with tunnel axis (can use guidewire or drill guide to create pilot path), or abandon screw and convert to button fixation. If divergence discovered post-operatively (CT scan or reoperation), management depends on symptoms: Asymptomatic divergence without PCL injury can observe (screw left in place if not causing problems). Symptomatic divergence or PCL injury requires screw removal and possible revision fixation or PCL reconstruction if PCL significantly damaged. PREVENTION: Start screw insertion aligned perfectly with femoral tunnel axis (screw introducer parallel to tunnel trajectory), use gentle controlled torque during insertion (high force can cause screw to wander especially in soft bone), consider pre-tapping tunnel in dense bone to create pilot path (tap provides guide for screw reducing divergence risk), arthroscopic visualization during screw insertion watching for screw tip emergence in joint (should not see screw). - BIOABSORBABLE SCREW BREAKAGE - screw fractures during insertion leaving fragment in tunnel. CONSEQUENCE: If broken fragment provides adequate fixation (greater than 15mm length engaged in tunnel) usually not clinically significant (fragment wedged creates friction fixation). If fragment loose or fixation inadequate from short fragment (less than 10mm), risk of fixation failure and graft pullout. Loose fragment can migrate causing synovitis or mechanical symptoms (rare). RECOGNITION: Feel or hear crack during screw insertion (brittle PLLA material fractures with distinct sound), sudden loss of resistance indicating screw no longer advancing, broken screw shaft visible on driver or protruding from tunnel. MANAGEMENT: If adequate fragment length in tunnel (greater than 15mm) providing fixation, can leave fragment and proceed (consider supplementing with backup tibial fixation for security). If inadequate fixation, attempt to remove broken fragment using screw extractor or grasping forceps (can be difficult if fragment wedged tightly), insert new screw if fragment removed, or convert to button fixation if screw removal unsuccessful or second screw not feasible. PREVENTION: Use controlled torque during insertion (hand driver rather than power driver reduces over-torque risk), avoid excessive insertion force (gentle steady pressure rather than forceful cranking), pre-tap tunnel if bone very dense (reduces insertion resistance), use metal screw in very hard bone if available (titanium does not break like bioabsorbable). - GRAFT LACERATION from screw threads - screw cuts or shears graft fibers during insertion weakening graft. CONSEQUENCE: Reduces graft tensile strength proportional to percentage of fibers cut (25 percent fibers cut equals approximately 25 percent strength loss), creates stress riser (damaged area concentrates stress and fails first during loading), increases failure risk especially in early post-operative period before graft healing. RECOGNITION: Arthroscopically visualize screw insertion (should see screw pass alongside graft wedging graft to one side - if screw passes through center of graft suggests laceration), after screw insertion see frayed or cut fibers on graft surface, resistance during screw insertion higher than expected (cutting through graft creates drag). MANAGEMENT: If minor laceration identified (less than 25 percent fibers estimated), can accept and reinforce with backup tibial fixation (over-the-top button tibial side or second screw). If major laceration (greater than 25-50 percent fibers), consider removing screw and using button femoral fixation instead (avoid further graft damage), or proceed with caution understanding higher failure risk and counsel patient. PREVENTION: Position screw ALONGSIDE graft not through center (eccentric screw placement wedging graft against opposite tunnel wall - screw on one side, graft on other side creates interference fixation without cutting graft), visualize graft and screw positions arthroscopically during insertion ensuring separation, use screw diameter appropriate for tunnel (oversized screw 2mm larger than tunnel compresses and cuts graft - use same diameter or maximum 1mm larger), gentle screw insertion technique. ### Step 9: Graft Tensioning and Knee Cycling Graft Tensioning and Knee Cycling: GOAL: Remove slack from graft construct, pre-tension graft to physiologic level, cycle knee through ROM to precondition graft before tibial fixation eliminating creep (gradual lengthening under load). RATIONALE: All grafts exhibit CREEP when first loaded (viscoelastic property of collagen - under constant load tendon gradually elongates over time reaching new equilibrium length after 20-30 load cycles). If tibial fixation performed before cycling, graft will creep post-fixation causing LAXITY (graft elongates creating increased knee translation and positive pivot shift). By cycling BEFORE tibial fixation, induce creep pre-fixation then fix graft at post-creep length eliminating post-operative laxity from creep. TECHNIQUE: With femoral fixation secure (button flipped and seated, or interference screw inserted), pull on tibial end of graft from anterior tibial incision applying 15-30 pounds tension (moderate firm pull - can use tensiometer for precise measurement but most surgeons estimate by feel). While maintaining tension on graft, cycle knee slowly through full ROM: 0 degrees full extension to 120-130 degrees flexion, repeated 20-30 cycles (each cycle equals extension to flexion back to extension). Watch arthroscopically during cycling: Graft should tighten and relax with knee motion (tight in extension for AM bundle component, relatively relaxed in deep flexion - normal biomechanics), graft should fill femoral and tibial tunnels throughout ROM without gapping (no space between graft and tunnel walls), graft should NOT contact or impinge on roof of intercondylar notch or lateral wall during extension (if impingement present indicates notchplasty needed or tibial tunnel too anterior - address before proceeding). After 20-30 cycles, graft will have undergone creep and reached equilibrium length (additional cycles produce no further lengthening). Maintain tension on tibial end of graft preparing for tibial fixation. OPTIMAL KNEE POSITION FOR TIBIAL FIXATION: Controversy exists regarding ideal knee flexion angle for tibial fixation. OPTIONS: (1) FULL EXTENSION 0 degrees - historic approach, rationale: ACL tightest in full extension so fixing graft in extension ensures adequate restraint to anterior translation throughout ROM, prevents post-operative flexion contracture. (2) 15-30 DEGREES FLEXION - most common current practice, rationale: Neutral position where graft isometric (equal tension throughout ROM without over-constraint), prevents over-tensioning graft (full extension can over-tighten graft causing graft stress, loss of flexion from over-constraint, graft failure), allows slight graft relaxation in deep flexion (physiologic). (3) 20 DEGREES FLEXION with anterior drawer reduced - some surgeons apply POSTERIOR force to tibia while knee flexed 20 degrees pushing tibia posteriorly to reduce any anterior subluxation then fix graft with tibia reduced (ensures ACL graft replacing anterior translation restraint). EVIDENCE: Multiple studies show NO significant difference in outcomes regardless of fixation angle within 0-30 degree range (all positions provide equivalent laxity, IKDC scores, return to sport). Avoid fixing in FLEXION greater than 30 degrees (causes graft over-constraint in extension potentially limiting extension or over-stressing graft) or EXTENSION less than 0 degrees (hyperextension can over-tension graft). Current CONSENSUS: 15-30 degrees flexion accepted standard. MAINTAIN KNEE POSITION: Use assistant or positioning device to hold knee at chosen angle (typically 20-30 degrees flexion), confirm angle visually and with goniometer, maintain position during tibial fixation (do not allow knee to move which would alter graft tension). FINAL TENSION ON GRAFT before tibial fixation: Pull tibial end of graft with 15-30 pounds force (moderate firm pull) removing all slack - graft should be taut but not over-tensioned (excessive tension greater than 50 pounds can damage graft or cause over-constraint). **Technical Tip**: EXAM KEY: 'GRAFT TENSIONING and KNEE CYCLING are critical steps preventing post-operative graft laxity from VISCOELASTIC CREEP phenomenon. CREEP defined: Time-dependent elongation of viscoelastic material under constant load (tendon collagen exhibits creep - when load applied tendon initially elongates elastically then continues to elongate slowly over time under constant load reaching new equilibrium length). BIOMECHANICS of creep in ACL grafts: Initial graft fixation creates pre-tension in graft (baseline tension approximately 50-100N depending on fixation tension applied). Under this constant in-vivo tension, graft undergoes creep over first 20-30 load cycles (knee flexion-extension cycles) elongating 2-5mm typically (hamstring grafts creep more than BTB grafts due to viscoelastic properties - hamstring tendon more compliant than bone blocks which minimal creep). After 20-30 cycles, creep plateaus and no further elongation occurs (graft reached new equilibrium length). CLINICAL CONSEQUENCE if NOT pre-cycled: If surgeon fixes graft at both ends (femoral and tibial fixation) without pre-cycling, graft undergoes creep post-operatively during early rehabilitation creating LAXITY (increased anterior tibial translation, positive pivot shift grade 1-2, patient perception of instability, possible functional limitation). Studies show non-cycled grafts have 2-3mm MORE laxity at 6 weeks post-op compared to pre-cycled grafts measured by KT-1000 arthrometer or stress radiographs. PREVENTION of creep-induced laxity: PRE-CYCLE graft BEFORE tibial fixation. Technique: After femoral fixation secure, pull graft tight from tibial end and cycle knee through full ROM (0-120 degrees) for 20-30 cycles inducing creep pre-fixation. Graft elongates during cycling reaching equilibrium. Then fix tibia with graft at post-creep length eliminating post-operative lengthening. CYCLING PARAMETERS: Number of cycles: Minimum 20 cycles required to induce full creep (studies show creep plateaus after 15-25 cycles), 25-30 cycles commonly used for safety margin. ROM: Full extension 0 degrees to maximum flexion 120-130 degrees (full ROM necessary to load graft through all positions inducing maximum creep). Tension: 15-30 pounds tension on tibial graft end during cycling (moderate tension replicating physiologic loading). KNEE FLEXION ANGLE FOR TIBIAL FIXATION debate: Three schools of thought: (1) FULL EXTENSION 0 degrees - historic standard from 1980s-1990s, rationale: Native ACL tightest in extension (max tension at 0 degrees) so fixing graft in extension ensures graft adequately restrains anterior translation throughout ROM, prevents flexion contracture post-op. PROBLEM: Can over-tension graft causing graft stress and possible graft failure over time (graft under excessive load if fixed too tight), can limit flexion if graft over-constrained (mechanical block to flexion from tight graft). (2) 15-30 DEGREES FLEXION - current most common practice 60-70 percent surgeons, rationale: Graft isometric position (equal tension throughout ROM), avoids over-tensioning, allows slight graft relaxation in deep flexion replicating native ACL biomechanics (AM bundle relaxes in flexion while PL bundle tightens - single bundle reconstruction cannot perfectly replicate this reciprocal pattern but 20-30 degrees flexion provides balance). (3) 20 DEGREES FLEXION with POSTERIOR DRAWER REDUCED - variant of flexion fixation, technique: Flex knee 20 degrees, apply posterior force on proximal tibia pushing tibia posteriorly reducing any anterior subluxation (eliminating anterior tibial translation), fix graft with tibia held reduced. Rationale: Ensures ACL graft replacing anterior restraint by fixing with tibia in reduced position mimicking native ACL function. EVIDENCE comparing fixation angles: Multiple biomechanical studies and RCTs show NO significant difference in outcomes (IKDC scores, KT-1000 laxity measurements, return to sport, graft failure rates) when comparing fixation at 0 degrees versus 15 degrees versus 30 degrees flexion - all provide equivalent stability if technique otherwise sound. Level 1 RCT by Yoshiya et al (2004) randomized 60 patients to 0 degrees versus 30 degrees fixation showing no difference in any outcome at 2 years. Meta-analysis by Hiemstra et al (2010) including 8 studies showed no advantage to any specific angle within 0-30 degree range. CURRENT CONSENSUS: Fixation between 0-30 degrees flexion all acceptable - most surgeons use 15-30 degrees based on preference and teaching. AVOID: Fixation in flexion greater than 30 degrees (over-constrains graft in extension potentially limiting extension or over-stressing graft leading to failure - absolutely contraindicated), fixation in hyperextension less than 0 degrees (over-tensions graft excessively - rare but possible if knee forced into hyperextension during fixation). EXAM QUESTION: Why is graft pre-cycling important before tibial fixation and what happens if not performed? ANSWER: Graft pre-cycling (20-30 knee flexion-extension cycles with graft under tension before tibial fixation) is critical to induce viscoelastic CREEP before fixing graft at tibial end. Creep is time-dependent elongation of collagen under constant load - when graft first loaded it elongates 2-5mm over first 20-30 cycles then plateaus. If graft fixed at both ends without pre-cycling, creep occurs post-operatively causing graft lengthening and LAXITY (increased anterior tibial translation measured as 2-3mm greater on KT-1000 compared to pre-cycled grafts, positive pivot shift grade 1-2, patient-perceived instability). By pre-cycling before tibial fixation, surgeon induces creep reaching graft equilibrium length, then fixes tibia with graft at post-creep length, eliminating subsequent lengthening post-operatively. Cycling parameters: 20-30 cycles minimum, 15-30 pounds tension, full ROM 0-120 degrees flexion-extension. Knee flexion angle for tibial fixation between 0-30 degrees (typically 15-30 degrees flexion current standard) - no evidence showing superiority of any specific angle within this range for clinical outcomes.' - GRAFT OVER-TENSIONING from excessive pull during cycling or fixation (greater than 50 pounds tension) - creates supraphysiologic graft tension exceeding native ACL forces. CONSEQUENCE: Graft failure from over-stress (excessive tension causes graft fibers to fail progressively over weeks to months - insidious graft elongation and eventual rupture typically 6-24 months post-op), loss of knee flexion from over-constraint (tight graft mechanically blocks flexion creating stiffness - patient cannot flex beyond 90-110 degrees despite therapy), accelerated graft degradation (high tension increases metabolic demand on graft during remodeling phase potentially impairing healing), pain from over-load. RECOGNITION: Intra-operatively feel resistance to knee flexion during cycling (knee difficult to flex beyond 90 degrees suggests graft too tight), arthroscopically see graft remain taut throughout ROM without normal relaxation in flexion (graft should relax slightly in deep flexion - if stays tight throughout indicates over-tension), post-operatively patient has loss of flexion (cannot achieve 120-130 degrees flexion by 6 weeks despite therapy), early graft failure. PREVENTION: Use appropriate tension during cycling and fixation (15-30 pounds moderate pull, can use tensiometer for precision), allow slight graft relaxation in deep flexion during cycling (indicates appropriate tension not over-tight), avoid fixing knee in extension 0 degrees with excessive pull, test ROM after tibial fixation before closing (knee should flex to 120-130 degrees without resistance - if limited flexion suggests over-tension requiring tibial fixation revision). MANAGEMENT if identified: Before closing if over-tension recognized (limited flexion ROM), release tibial fixation and re-fix with less tension. Post-operatively if persistent flexion loss despite therapy (greater than 3 months post-op with flexion less than 110 degrees), may need manipulation under anesthesia (MUA) to break adhesions or arthroscopic lysis of adhesions (LOA) with possible graft revision if graft over-constraint causative. - UNDER-TENSIONING graft (insufficient tension less than 10 pounds during cycling/fixation) - graft fixed with slack in construct. CONSEQUENCE: Post-operative LAXITY (increased anterior tibial translation from baseline graft laxity plus additional creep, positive pivot shift grade 2-3, functional instability limiting activities), graft does not adequately restrain tibia creating recurrent instability symptoms, possible early graft failure from abnormal loading patterns (slack graft loaded in impact fashion rather than gradual loading causing sudden high stress). RECOGNITION: Intra-operatively arthroscopically see graft loose or redundant in tunnel (gapping between graft and tunnel walls), excessive ROM during cycling (knee flexes to 140-150 degrees easily suggesting insufficient graft tension), post-operatively increased laxity on exam (positive Lachman grade 2-3, positive pivot shift grade 2-3, KT-1000 side-to-side difference greater than 5mm indicating excessive translation). PREVENTION: Apply adequate tension (15-30 pounds moderate firm pull) during cycling and fixation removing all visible slack from graft, arthroscopic visualization confirms graft fills tunnels without gapping, perform Lachman and pivot shift tests on table after fixation confirming stability (should be negative or trace grade 1 maximum - if grade 2-3 laxity present indicates under-tension requiring fixation revision). MANAGEMENT if identified: Intra-operatively if under-tension recognized before closing, release tibial fixation and re-fix with increased tension. Post-operatively if symptomatic laxity (positive pivot shift, functional instability), may need revision ACL reconstruction. - GRAFT IMPINGEMENT on intercondylar notch roof or lateral wall during cycling - graft contacts bone during terminal extension creating mechanical block. CONSEQUENCE: Extension loss (cannot achieve 0 degrees extension due to graft impingement on roof or lateral wall), cyclops lesion formation (impingement stimulates fibrous proliferation creating nodule), graft abrasion and failure over time (repetitive contact wears graft fibers causing weakening and eventual rupture), quadriceps shutdown from inability to fully extend, patellofemoral pain and arthritis. RECOGNITION during cycling: Arthroscopically see graft contact anterior roof or lateral wall when knee brought to full extension (graft should not touch roof or walls - should have clear space), feel resistance to terminal extension (soft endpoint at 5-10 degrees flexion rather than firm endpoint at 0 degrees indicating mechanical block), patient cannot achieve full extension on table. MANAGEMENT: If impingement identified during cycling, MUST address before tibial fixation and closing: (1) Perform or extend notchplasty (remove bone from lateral wall or anterior roof creating clearance for graft - typically need 2-3mm clearance minimum), (2) Adjust tibial tunnel position if too anterior (may require abandoning tibial tunnel and drilling new tunnel in more posterior position if current tunnel critically anterior - rare indication), (3) Confirm full extension achieved after notchplasty (bring knee to 0 degrees and verify graft clears roof and walls arthroscopically). Never leave OR accepting extension loss - must achieve 0 degrees full extension before closing (non-negotiable endpoint). PREVENTION: Position tibial tunnel at anatomic footprint center (not too anterior), perform selective notchplasty if narrow notch or impingement risk during initial arthroscopy, check for impingement during cycling before tibial fixation allowing correction if needed. ### Step 10: Tibial Fixation Tibial Fixation: GOAL: Securely fix tibial end of graft in tibial tunnel with fixation strong enough to allow early rehabilitation protocols without pullout or failure during healing phase (6-12 weeks until graft-bone healing provides biological fixation). With knee held at chosen position (typically 20-30 degrees flexion) and graft tensioned (15-30 pounds moderate pull on tibial graft end), perform tibial fixation. TWO main tibial fixation methods: (1) INTERFERENCE SCREW fixation (bioabsorbable or metal screw inserted alongside graft in tibial tunnel) - most common method 70-80 percent surgeons. (2) FIXATION OVER BONE BRIDGE or on anterior tibia with post screw, spiked washer, or button (backup fixation). INTERFERENCE SCREW TIBIAL FIXATION TECHNIQUE: Select interference screw: Diameter same as tibial tunnel (8mm tunnel uses 8mm screw, 9mm tunnel uses 9mm screw) or 1mm larger (9mm screw in 8mm tunnel for tighter interference - less common), Length should be 25-35mm (typical tibial tunnel depth 40-50mm so screw 5-15mm shorter than tunnel preventing screw from penetrating too deep and exiting posterior tibial cortex risking popliteal vessel or nerve injury). Material: Bioabsorbable (PLLA or PLGA copolymers) most common current practice (gradual resorption over 12-24 months replaced by bone, eliminates retained hardware, avoids interference with future imaging or surgery), Metal (titanium) alternative (stronger, permanent but MRI artifact and may complicate future surgery). PREPARATION: Ensure graft under tension (15-30 pounds pull on sutures attached to tibial graft end protruding from anterior tibial incision), knee held at fixation angle (20-30 degrees flexion typically). INSERT SCREW through anterior tibial incision into tibial tunnel: Position screw ALONGSIDE graft (eccentric placement - screw on one side of tunnel, graft on opposite side creating interference wedge effect between screw threads and tunnel bone). Do NOT insert screw through center of graft (would lacerate fibers weakening graft). Use screw driver to advance screw into tibial tunnel parallel to tunnel axis and graft. CRITICAL TECHNIQUE: Screw should wedge graft against opposite tunnel wall (compression fixation). Advance screw slowly with controlled torque watching for: (1) Screw advancement (should progress steadily into tunnel at rate of 1-2mm per full screw driver rotation), (2) Graft position (graft should stay alongside screw not wrap around screw which indicates graft twisting or poor screw position), (3) Resistance (steady moderate resistance indicates screw engaging bone and compressing graft - sudden loss of resistance suggests posterior cortex penetration or screw divergence). DEPTH: Advance screw until screw head sits flush with anterior tibial cortex or slightly recessed 2-3mm (recessed reduces palpability and irritation over anterior tibia). Typical depth 25-35mm from anterior cortex. AVOID over-advancing: Screw deeper than 35-40mm risks penetrating posterior tibial cortex (popliteal vessels and tibial nerve located just posterior to tibia separated only by popliteus muscle and thin posterior capsule - screw penetration can cause catastrophic vascular or nerve injury). Use depth markings on screw driver or pre-measured depth stop to control advancement. CONFIRM FIXATION: After screw inserted, release tension on graft sutures - graft should remain in place without pullout (screw compression holds graft). Pull on sutures with moderate force (10-20 pounds) testing fixation security (graft should not pull out - if pulls out indicates inadequate screw purchase and need to revise fixation with larger screw or backup fixation). Cycle knee through ROM 10-20 cycles confirming graft stays fixed without motion. BACKUP TIBIAL FIXATION (if using): Some surgeons add BACKUP fixation on anterior tibia for extra security especially with soft bone, large diameter grafts, or revision surgery. Options: (1) POST SCREW with spiked washer - screw with large spiked washer inserted into anterior tibia adjacent to tibial tunnel over graft sutures securing sutures to bone (creates backup fixation point if interference screw fails). (2) SUTURE BUTTON - button similar to femoral button deployed on anterior tibia cortex with graft sutures passed through button (suspensory tibial fixation mirroring femoral technique). (3) SCREW AND WASHER over bone bridge - if tibial tunnel has bone bridge anterior to tunnel (interference screw in tunnel, bone bridge anterior to tunnel exit site), can place screw with washer over bone bridge securing graft sutures to bridge (historical technique less common now). HYBRID FIXATION (interference screw plus backup): Provides maximum fixation strength (600-1000N combined pullout strength exceeding physiologic ACL loads), redundancy if one fixation fails (backup prevents catastrophic failure), but added complexity and cost. Not routinely necessary for primary ACL reconstruction with good bone quality and proper technique (interference screw alone provides adequate 400-800N fixation strength). Consider hybrid in: Revision ACL with bone loss or tunnel widening (compromised bone quality reducing screw holding), very large diameter grafts (greater than 10mm where single screw may not provide adequate compression), osteoporotic or poor quality bone (elderly patient or rheumatoid arthritis patient where bone weak). FINAL ASSESSMENT after tibial fixation: (1) Graft fixed securely at both femoral and tibial ends (no pullout with moderate tension test), (2) Knee achieves full ROM - 0 degrees full extension (non-negotiable must achieve full extension before closing or have extension loss complication post-op) to 120-130 degrees flexion (normal physiologic flexion), (3) Stability tests negative - Lachman test NEGATIVE (no anterior tibial translation or firm endpoint grade 0-1 maximum acceptable, grade 2-3 indicates under-tension or fixation failure requiring revision), Pivot shift test NEGATIVE (no pivot or clunk grade 0-1 acceptable, grade 2-3 indicates inadequate stability needing revision), (4) Graft appearance good arthroscopically (fills tunnels, no impingement, no twisting, smooth without fraying), (5) No complications (no vascular injury, no nerve injury, no graft damage). **Technical Tip**: EXAM KEY: 'TIBIAL INTERFERENCE SCREW FIXATION most common method in ACL reconstruction (used by 70-80 percent surgeons) due to simplicity, low cost, adequate fixation strength, and bone-to-tendon healing potential. BIOMECHANICAL PROPERTIES: Tibial interference screw pullout strength typically 400-800N (varies with screw diameter 7-9mm, screw length 20-35mm, bone density, and technique). This exceeds forces during early rehabilitation (physiologic ACL forces during walking 200-400N, during stair climbing 400-600N - graft not subjected to maximal forces 2000N until high-demand activities like sprinting and jumping typically avoided for 4-6 months post-op allowing graft-bone healing to develop). FIXATION MECHANISM: Screw threads engage cancellous bone of tibial tunnel wall creating friction (mechanical interlock between screw threads and trabeculae), screw wedges graft against opposite tunnel wall creating compression (compression plus friction equals interference fixation), graft-bone interface under compression enhances healing (compression stimulates osteoblast activity and collagen ingrowth at graft-bone junction - biological fixation develops over 6-12 weeks replacing mechanical fixation). OPTIMAL SCREW PLACEMENT TECHNIQUE: Screw inserted ALONGSIDE graft not through center (eccentric screw position wedging graft to opposite wall provides better compression and avoids graft laceration from threads). Studies show eccentric screw placement provides 15-25 percent HIGHER pullout strength compared to central screw placement (eccentric creates true wedge compression while central mainly just compresses graft without wedging). Arthroscopic visualization during screw insertion confirms position: Looking from AL portal into tibial tunnel aperture, should see screw advance on ONE side of tunnel (left or right, surgeon choice) with graft displaced to OPPOSITE side compressed against tunnel wall. If screw centered in tunnel with graft surrounding screw circumferentially, indicates suboptimal technique (central placement risks graft laceration and provides less compression). SCREW DIVERGENCE RISKS: Similar to femoral side, tibial screw can diverge from intended tunnel trajectory exiting posteriorly (penetrating posterior cortex risking popliteal injury) or laterally/medially (creating cortical breach weakening fixation). POSTERIOR DIVERGENCE most dangerous: Posterior tibia contains POPLITEAL ARTERY and VEIN (major vessels supplying lower leg - injury can cause limb-threatening ischemia requiring emergency vascular surgery), TIBIAL NERVE (nerve injury causes foot drop from motor loss plus sensory deficit), POPLITEUS MUSCLE (less critical structure). INCIDENCE of popliteal injury from tibial screw: Rare but catastrophic (reported incidence 0.1-0.5 percent less than 1 in 200 cases - exact incidence unknown due to underreporting and medico-legal concerns). CASE REPORTS: Multiple published cases of popliteal artery pseudoaneurysm (arterial wall injury creating expanding hematoma that can rupture or thrombose), arterial laceration with hemorrhage requiring emergency repair, arterial thrombosis causing acute limb ischemia, tibial nerve palsy from direct nerve transection or compression from hematoma. PREVENTION: (1) Limit screw length to 25-35mm (measure tibial tunnel depth with gauge, use screw 5-15mm shorter than tunnel ensuring screw stays intra-tunnel), (2) Control screw insertion depth (use depth stop on screw driver or count rotations calculating depth 2mm advancement per rotation for typical screw pitch), (3) Align screw with tunnel axis (screw trajectory parallel to tunnel prevents divergence), (4) Monitor resistance during insertion (sudden loss of resistance suggests cortex penetration - stop immediately and assess), (5) Fluoroscopic confirmation if uncertain (lateral fluoroscopy shows screw position relative to posterior tibial cortex - screw tip should be anterior to posterior cortex not penetrating). RECOGNITION of posterior penetration: During screw insertion feel sudden loss of resistance indicating cortex breach (should have steady moderate resistance if screw staying intra-tunnel), inability to advance screw to expected depth (screw stops short or advances too easily), post-operative signs of vascular injury (expanding calf hematoma, loss of distal pulses, foot ischemia, pain out of proportion), signs of nerve injury (foot drop, numbness). MANAGEMENT: If recognized intra-operatively (loss of resistance during insertion), STOP immediately and remove screw before fully inserting, confirm screw length appropriate and tunnel depth measured correctly, re-insert shorter screw or use backup tibial fixation avoiding interference screw. If vascular injury suspected post-operatively (expanding hematoma, diminished pulses, ischemia), URGENT vascular surgery consultation for angiography and possible repair (delay can result in limb loss). BIOABSORBABLE versus METAL SCREWS for tibial fixation: BIOABSORBABLE advantages: Gradual resorption over 12-24 months (PLLA) or 6-12 months (PLGA) replaced by bone (eliminates retained hardware avoiding long-term complications like screw migration, pain from prominent screw, interference with future imaging MRI no artifact from plastic versus metal causes significant artifact), no removal needed (metal screw may need removal if prominent or painful requiring second surgery in 5-10 percent cases), no complication if revision ACL needed years later (metal screw complicates revision tunnel placement or fixation). BIOABSORBABLE disadvantages: Lower strength than metal (pullout strength bioabsorbable 400-600N versus metal 600-900N for same size screw - clinically both adequate for rehabilitation but metal higher safety margin), breakage during insertion (brittle PLLA fractures in 5-15 percent insertions from excessive torque though usually not clinically significant if fragment provides some fixation), inflammatory foreign body reaction (sterile effusion or synovitis in 1-5 percent cases from particulate debris during resorption - typically self-limited resolving over weeks, rarely requires screw removal), incomplete resorption (some bioabsorbable screws do not fully resorb leaving fragments visible on MRI or CT years later though usually asymptomatic). METAL screw advantages: Higher strength (titanium provides 20-30 percent higher pullout than bioabsorbable), no breakage (ductile metal bends rather than fractures - insertion reliable), no foreign body reaction (biocompatible titanium well tolerated). METAL disadvantages: Permanent hardware (retained forever unless removed creating future complications like pain from prominence 5-10 percent, screw migration rare less than 1 percent, interference with MRI imaging moderate artifact degrades image quality), may need removal (5-10 percent patients request removal for pain or irritation requiring second surgery), complicates revision ACL (metal screw in tunnel interferes with revision tunnel placement - may need removal before revision). CURRENT PRACTICE: Most surgeons use BIOABSORBABLE screws (approximately 70-80 percent) for tibial fixation given advantages of no retained hardware and adequate fixation strength with proper technique. Metal screws used selectively for cases needing maximum strength (revision ACL, poor bone quality, high-demand athlete) or surgeon preference. EXAM QUESTION: Compare bioabsorbable versus metal interference screws for tibial ACL fixation including biomechanical properties, advantages, disadvantages, and complications. ANSWER: Bioabsorbable screws (PLLA or PLGA polymers) provide pullout strength 400-600N adequate for post-operative rehabilitation (physiologic ACL forces 200-600N during early activities), gradually resorb over 6-24 months replaced by bone eliminating retained hardware, avoid MRI artifact and future surgical interference, but have disadvantages of lower strength than metal (20-30 percent weaker), risk breakage during insertion (5-15 percent from brittle material), and possible inflammatory foreign body reaction (1-5 percent sterile effusion during resorption). Metal screws (titanium) provide higher pullout strength 600-900N (20-30 percent stronger than bioabsorbable), no breakage risk (ductile material), and no foreign body reaction, but disadvantages include permanent hardware (may cause long-term pain from prominence requiring removal in 5-10 percent, MRI artifact degrading image quality, complicates future revision ACL surgery requiring screw removal before revision tunnel placement). Clinical outcomes equivalent between bioabsorbable and metal screws when technique proper (multiple RCTs show no difference in stability, IKDC scores, or failure rates at 2-5 years). Current practice favors bioabsorbable screws (70-80 percent surgeons) due to benefits of no long-term hardware complications despite slightly lower strength. Metal reserved for cases requiring maximum strength (revision ACL, osteoporotic bone, high-demand athlete) or surgeon preference.' - POPLITEAL VASCULAR INJURY from tibial screw penetrating posterior cortex (CATASTROPHIC complication 0.1-0.5 percent incidence) - screw advances too deep penetrating posterior tibial cortex lacerating or puncturing popliteal artery or vein. CONSEQUENCE: Acute hemorrhage (arterial laceration causes rapid blood loss into posterior compartments presenting as expanding tense calf hematoma, hypotension if severe), pseudoaneurysm formation (arterial wall injury creates contained hematoma that can expand over days to weeks and rupture or thrombose), arterial thrombosis (complete vessel occlusion from injury causing acute limb ischemia - loss of distal pulses, cold pale foot, pain), compartment syndrome (expanding hematoma increases compartment pressure causing muscle and nerve ischemia requiring emergency fasciotomy), limb loss if not recognized and treated emergently (delay in vascular repair can lead to irreversible ischemia and amputation - time critical). RECOGNITION: Intra-operative signs: Sudden loss of resistance during screw insertion (should have steady resistance if intra-tunnel, sudden ease indicates cortex penetration), inability to advance screw to expected depth or excessive ease advancing, visualization of blood in surgical field if arterial injury (pulsatile bleeding from tibial tunnel or incision if major laceration). Post-operative signs: Expanding tense calf hematoma (progressive painful swelling posterior calf starting within hours post-op), diminished or absent distal pulses (dorsalis pedis or posterior tibial pulse weak or absent compared to contralateral limb indicating arterial compromise), foot ischemia (cold pale foot, delayed capillary refill greater than 3 seconds, sensory deficit, pain out of proportion to expected post-op pain), signs of compartment syndrome (tense swollen compartments, pain with passive motion, paresthesias). MANAGEMENT: If suspected intra-operatively (loss of resistance during screw insertion), STOP immediately and remove screw before fully seated, do NOT re-attempt screw at same depth (use shorter screw or backup fixation), consider intra-operative angiography or vascular surgery consultation if high suspicion (confirm vessel integrity before closing). If identified post-operatively (expanding hematoma, lost pulses, ischemia), IMMEDIATE vascular surgery consultation (do not delay - call vascular surgery emergently), obtain CT angiography or formal angiography urgently to define injury (identifies arterial laceration, pseudoaneurysm, or thrombosis and guides treatment), treatment depends on injury: Arterial laceration requires urgent open repair (posterior approach to popliteal fossa, vessel exploration, primary repair or interposition graft if gap), pseudoaneurysm may require open repair or endovascular coiling, arterial thrombosis requires thrombectomy or bypass. Delay in treatment (greater than 6-8 hours from onset of ischemia) significantly increases amputation risk (irreversible muscle and nerve damage occurs after 6 hours warm ischemia time - limb salvage rate drops from 95 percent if repaired within 6 hours to 50-70 percent if delayed beyond 8 hours). PREVENTION: (1) Use tibial screw length 5-15mm SHORTER than measured tibial tunnel depth (measure tunnel carefully with depth gauge from anterior cortex to posterior cortex exit on plateau - typical 40-50mm, use 25-35mm screw), (2) Control screw insertion depth (use depth stop or markings on driver, count rotations calculating advancement 2mm per rotation), (3) Monitor resistance continuously during insertion (steady resistance indicates intra-tunnel, sudden loss indicates cortex breach - stop immediately), (4) Align screw parallel to tunnel axis (divergent screw can exit posteriorly even if length appropriate), (5) Consider fluoroscopy if uncertain (lateral fluoroscopy confirms screw position anterior to posterior tibial cortex). MEDICO-LEGAL: Popliteal injury from tibial screw is NEVER acceptable complication (considered preventable technical error - no excuse for advancing screw beyond safe depth when tunnel measured and screw length selected appropriately), high liability risk if occurs (devastating injury with permanent disability or limb loss creates large damages), proper documentation critical (operative note must describe tunnel depth measurement, screw length selection rationale, depth control during insertion). - TIBIAL NERVE INJURY from posterior screw penetration or hematoma compression - nerve damage causing foot drop and sensory loss. CONSEQUENCE: Motor deficit (foot drop from tibial nerve motor branches to gastrocnemius, soleus, posterior tibialis causing inability to plantarflex foot or stand on tiptoes - severe functional limitation), sensory deficit (numbness plantar foot and toes from tibial nerve sensory distribution), chronic neuropathic pain (dysesthesias, burning pain along nerve distribution), permanent disability if nerve transected (requires nerve repair or grafting with poor recovery prognosis). RECOGNITION: Post-operative foot drop (patient cannot plantarflex foot against resistance, cannot stand on tiptoes, weak push-off during gait), numbness plantar aspect of foot and toes (patient reports decreased sensation when tested with monofilament or pinprick), signs of nerve injury on physical exam (weakness of gastrocnemius, soleus, tibialis posterior muscles; sensory deficit in tibial nerve distribution; absent Achilles reflex). MANAGEMENT: If recognized immediately post-op (foot drop noted in recovery room), urgent exploration if direct nerve injury suspected from screw (remove screw, explore popliteal fossa, assess nerve integrity - if transected perform primary repair or nerve grafting, if intact but compressed from hematoma decompress hematoma evacuating blood relieving pressure), if nerve intact without transection or compression can observe with expectation of recovery over 3-6 months (neurapraxia or axonotmesis recovers with time - support with AFO brace for foot drop), EMG/NCS at 3-6 weeks to assess severity and prognosis. PREVENTION: Same as vascular injury prevention (limit screw depth, control insertion, monitor resistance, use fluoroscopy if needed). - Graft LACERATION from screw threads cutting fibers - screw inserted through center of graft rather than alongside. CONSEQUENCE: Weakens graft (fiber disruption reduces tensile strength proportionally - 25 percent fibers cut equals 25 percent strength loss), creates stress concentration (damaged area fails first under loading), increases early failure risk. RECOGNITION: Arthroscopically see screw emerge in tibial tunnel aperture with graft surrounding screw circumferentially (indicates screw through graft center rather than eccentric alongside), after screw insertion see frayed or cut fibers on graft surface, higher resistance during screw insertion (cutting through graft creates drag). MANAGEMENT: If recognized before screw fully seated, remove screw and re-insert alongside graft eccentrically (reposition screw laterally or medially to one side of tunnel with graft on opposite side), if recognized after screw fully seated may accept if minor laceration (less than 25 percent fibers) and reinforce with backup tibial fixation, if major laceration (greater than 25-50 percent fibers) consider removing screw and using backup button tibial fixation to avoid additional graft damage. PREVENTION: Position screw ALONGSIDE graft eccentrically (screw on lateral or medial side of tunnel, graft on opposite side), visualize arthroscopically during insertion confirming screw separate from graft, use screw diameter appropriate (same as tunnel or maximum 1mm larger - oversized screw compresses and cuts graft). - BIOABSORBABLE SCREW BREAKAGE - screw fractures during insertion leaving fragment in tunnel. CONSEQUENCE: Usually not clinically significant if adequate fragment length provides fixation (greater than 15mm engaged in tunnel), but if short fragment (less than 10mm) inadequate fixation risks graft pullout, loose fragments can cause synovitis or mechanical symptoms (rare). RECOGNITION: Feel or hear crack during insertion (brittle PLLA material fractures with characteristic sound), sudden loss of resistance indicating screw no longer advancing, see broken screw shaft on driver or protruding from incision. MANAGEMENT: If adequate fragment providing fixation (greater than 15mm), can leave and supplement with backup tibial fixation (post screw or button for security), if inadequate fixation attempt to remove fragment with screw extractor or forceps and insert new screw or convert to backup fixation. PREVENTION: Controlled torque (avoid excessive force), pre-tap tunnel in dense bone (reduces insertion resistance), use metal screw in very hard bone if bioabsorbable breaking repeatedly. ### Step 11: Final Assessment and ROM Confirmation Final Assessment and ROM Confirmation: GOAL: Confirm ACL reconstruction successfully completed with adequate stability, full ROM, proper graft position and tension, no complications before closing and ending procedure. This final assessment critical quality checkpoint - identification of problems now allows correction before closing, missing problems leads to post-operative complications and possible revision surgery. SYSTEMATIC FINAL CHECKS: (1) FULL EXTENSION ACHIEVEMENT (MOST CRITICAL CHECKPOINT - extension loss is NEVER acceptable): Bring knee to full extension 0 degrees (may need assistant to apply extension force or place bump under heel allowing gravity extension). CONFIRM full extension: Visually assess knee extended flat on bed (no flexion contracture visible), use goniometer measuring 0 degrees extension (not 5 degrees or 10 degrees - must be true 0 degrees full extension matching contralateral knee), arthroscopically visualize graft position in terminal extension (graft should NOT impinge on anterior roof of intercondylar notch or lateral wall - should have 2-3mm clearance minimum), feel extension endpoint (should be firm bony endpoint indicating full extension, soft springy endpoint suggests mechanical block preventing full extension from impingement or over-constraint). IF EXTENSION LOSS PRESENT (cannot achieve 0 degrees): MUST identify cause and correct before closing - DO NOT accept extension loss "will improve with therapy" (will NOT improve if mechanical cause, leads to quadriceps shutdown, patellofemoral pain, arthritis, poor outcome, possible litigation). CAUSES of extension loss and MANAGEMENT: (a) GRAFT IMPINGEMENT on roof or lateral wall (most common cause) - graft too anterior or inadequate notchplasty. CORRECTION: Perform or extend notchplasty removing bone from anterior roof or lateral wall creating clearance (typically need 2-3mm minimum clearance), confirm clearance arthroscopically after notchplasty (see graft clear roof throughout extension), re-test extension achieving 0 degrees. (b) GRAFT OVER-CONSTRAINT from excessive tension - graft fixed too tight preventing extension. CORRECTION: Release tibial fixation, reduce graft tension (less pull on tibial graft end), re-fix tibia with appropriate tension, re-test extension. (c) CYCLOPS LESION from inadequate ACL stump debridement - residual anterior stump creates nodule. CORRECTION: Debride remaining ACL stump or fibrous tissue using motorized shaver and radiofrequency device removing anterior soft tissue blocking extension, re-test extension. (d) HEMARTHROSIS - large blood clot in joint creates stiffness. CORRECTION: Irrigate joint copiously evacuating blood and clots, re-test extension. (e) FEMORAL TUNNEL TOO ANTERIOR - creates vertical graft prone to impingement. CORRECTION: May need to abandon reconstruction and re-drill femoral tunnel posteriorly (major revision intra-operatively but necessary if tunnel critically malpositioned), or perform aggressive notchplasty accepting suboptimal graft position. NEVER LEAVE OR WITH EXTENSION LOSS - this single checkpoint prevents most common ACL reconstruction complication (extension loss). (2) ADEQUATE FLEXION: Flex knee to 120-130 degrees (normal physiologic flexion) confirming no mechanical block or over-constraint limiting flexion. IF FLEXION LIMITED (cannot achieve 120 degrees): Identify cause: (a) Graft over-tensioned - release tibial fixation and re-fix with less tension. (b) Pain or muscle guarding - adequate anesthesia should eliminate pain allowing full passive flexion (if not, may need deeper anesthesia or muscle relaxation). (c) Adhesions from prolonged case or manipulation - debride adhesions arthroscopically (rare during initial reconstruction, more common in revision or repeat arthroscopy). Typical accept minimum 120 degrees flexion before closing (mild flexion limitation less problematic than extension loss - flexion usually improves with therapy while extension loss does not). (3) STABILITY TESTING: Perform LACHMAN TEST - patient supine with knee 20-30 degrees flexion, stabilize distal femur with one hand, pull proximal tibia anteriorly with other hand assessing anterior tibial translation and endpoint. EXPECTED result: NEGATIVE Lachman (no anterior translation or firm endpoint grade 0), or trace anterior translation with firm endpoint (grade 1 acceptable). UNACCEPTABLE: Grade 2 (5-10mm anterior translation with soft endpoint) or grade 3 (greater than 10mm anterior translation with no endpoint) indicates inadequate graft tension or fixation failure - MUST revise before closing (release and re-fix tibia with more tension, or check femoral fixation if button not flipped or screw diverged). Perform PIVOT SHIFT TEST - patient supine completely relaxed under anesthesia (muscle guarding must be eliminated for valid test), flex hip 20-30 degrees, internally rotate tibia, apply valgus stress to knee, slowly flex knee from full extension toward 90 degrees feeling for "clunk" or "shift" of lateral tibial plateau reducing from subluxed to reduced position. EXPECTED result: NEGATIVE pivot shift (no clunk or shift, smooth motion throughout flexion arc grade 0), or trace shift barely palpable (grade 1 acceptable). UNACCEPTABLE: Grade 2 (moderate clunk felt but not visible) or grade 3 (gross clunk visible and felt "jump sign") indicates inadequate rotational stability from graft malposition (femoral tunnel too anterior) or under-tension - requires revision (check femoral tunnel position, check graft tension, may need to abandon and re-drill femoral tunnel if critically anterior, or increase tibial tension if under-tensioned). NOTE: Pivot shift test most sensitive and specific test for ACL function (better predictor of functional stability than Lachman or drawer) - positive post-operative pivot shift correlates with poor functional outcomes and patient dissatisfaction. (4) ARTHROSCOPIC INSPECTION: View graft from AL and AM portals systematically: Femoral tunnel aperture - graft should fill tunnel completely without gaps (tight graft-bone interface), graft positioned at anatomic footprint center (10-11 o'clock right knee), no graft fraying or damage visible, graft does not pull out of tunnel with ROM (stable fixation). Intra-articular graft course - graft should be smooth and uniform without twisting (suture pattern runs straight along graft confirming no twisting), graft tensioned appropriately (taut in extension relaxes slightly in flexion normal biomechanics), graft does not impinge on PCL or menisci during ROM. Tibial tunnel aperture - graft fills tunnel completely, smooth tunnel edges without sharp corners abrading graft, no graft fraying, graft stable without pullout. General joint inspection - no loose bodies or debris from bone or graft preparation, menisci intact without iatrogenic injury, articular cartilage intact without damage from instrumentation, ligaments intact (MCL, LCL, PCL visualized and intact), adequate hemostasis (no active bleeding from soft tissues, capsule, or bone). (5) FINAL ROM UNDER DIRECT VISUALIZATION: Cycle knee through full ROM (0 degrees extension to 130 degrees flexion) 10-20 times while viewing arthroscopically confirming: Graft clears intercondylar notch roof and lateral wall throughout ROM (no impingement at any flexion angle), graft does not contact or abrade on PCL during flexion-extension cycles, graft remains in tunnels without pullout (stable fixation), graft behavior physiologic (tightens in extension, relaxes in flexion). (6) DOCUMENT ALL FINDINGS: Record in operative note: Femoral tunnel position (clock face position measured - example "10:30 right knee"), femoral tunnel length and diameter (example "32mm length, 8mm diameter"), femoral fixation method and device (example "Endobutton CL button fixation, button flipped confirmed"), tibial tunnel position (anatomic footprint center, relation to PCL and meniscus), tibial tunnel length and diameter (example "45mm length, 8mm diameter"), tibial fixation method and device (example "8mm x 28mm bioabsorbable PLLA interference screw"), final graft tension (example "20 pounds tension at 20 degrees flexion"), final ROM achieved (example "0 degrees extension to 135 degrees flexion full ROM"), final stability testing (example "Lachman negative grade 0, pivot shift negative grade 0"), any complications or intra-operative events (example "none" or describe issue and management). (7) PREPARE FOR CLOSURE: Irrigate joint with copious saline (3-5 liters minimum removing all debris, bone chips, blood), remove all instruments from joint, perform final arthroscopic sweep visualizing all compartments clear, deflate tourniquet (if used) and achieve hemostasis (cauterize bleeding vessels, ensure no active arterial or venous bleeding), remove arthroscope. **Technical Tip**: EXAM KEY: 'FINAL ASSESSMENT before closing is CRITICAL QUALITY CHECKPOINT preventing post-operative complications from intra-operative technical errors. Most common missed finding: EXTENSION LOSS from graft impingement (occurs in 5-15 percent ACL reconstructions if not checked rigorously before closing, leads to devastating complications quadriceps shutdown, patellofemoral arthritis, cyclops lesion formation, patient dissatisfaction, possible litigation). IMPERATIVE: NEVER leave operating room accepting ANY extension loss - must achieve full 0 degrees extension matching contralateral knee before closing (non-negotiable endpoint). Even 3-5 degrees extension loss that seems minor intra-operatively causes major post-operative problems: QUADRICEPS SHUTDOWN (neurologic inhibition - inability to fully activate quadriceps if knee not achieving full extension creates reflex inhibition of quadriceps motor neurons at spinal cord level reducing quadriceps strength by 30-50 percent despite physical therapy), PATELLOFEMORAL PAIN (altered patellofemoral mechanics from extension loss increases contact stress on patella causing anterior knee pain becoming chronic), PATELLOFEMORAL ARTHRITIS (accelerated cartilage degeneration from abnormal loading patterns - extension loss changes patellofemoral contact pressures by 200-300 percent increasing peak stress), GAIT ABNORMALITY (patient cannot fully extend knee during stance phase creating limp and compensatory hip/ankle mechanics), FUNCTIONAL LIMITATION (unable to run normally, jump, or perform sports requiring full extension). CONSEQUENCE: Extension loss single most common reason for patient dissatisfaction after ACL reconstruction (worse than graft failure in terms of functional impact) and litigation (deviation from standard of care if surgeon leaves OR with extension loss and does not address before closing). EXAM SCENARIO: You perform ACL reconstruction and at end of case patient has 5 degrees extension loss. What do you do? WRONG ANSWER: "Close and plan for aggressive extension therapy post-operatively - should improve with therapy." Why wrong: Mechanical extension loss from impingement or over-constraint will NOT improve with therapy (therapy cannot remove bone causing impingement or release over-tensioned graft). Patient will have permanent extension deficit leading to complications above. CORRECT ANSWER: "Do NOT close - identify cause of extension loss and correct intra-operatively before closing. Systematic assessment: (1) Arthroscopically visualize graft in terminal extension - if graft impinging on anterior roof of intercondylar notch or lateral wall indicates inadequate notchplasty or tibial tunnel too anterior, perform or extend notchplasty removing bone from impingement site creating 2-3mm clearance minimum, re-check extension after notchplasty until achieve 0 degrees. (2) Assess graft tension - if graft over-tensioned (remains taut throughout ROM without relaxation in flexion), release tibial fixation and re-fix with reduced tension allowing appropriate laxity, re-check extension. (3) Inspect for residual ACL stump or cyclops lesion - if anterior soft tissue nodule present, debride with motorized shaver and radiofrequency removing tissue, re-check extension. (4) Evaluate femoral tunnel position - if femoral tunnel too anterior (11-12 o'clock instead of 10-11 o'clock right knee) creating vertical graft prone to impingement, may need to abandon reconstruction and re-drill femoral tunnel posteriorly at 10 o'clock position (major intra-operative revision but necessary if tunnel critically malpositioned), or perform aggressive notchplasty accepting suboptimal position if re-drilling not feasible. Only after achieving full 0 degrees extension can proceed with closure." PIVOT SHIFT TEST UNDER ANESTHESIA - most important stability test (more predictive of functional outcome than Lachman or drawer). TECHNIQUE CRITICAL: Patient must be completely relaxed under adequate anesthesia (muscle guarding prevents valid test - awake or tense patient has involuntary hamstring contraction preventing pivot shift even with ACL deficiency, need deep anesthesia or muscle relaxant ensuring complete muscle relaxation). GRADING: Grade 0 (negative) equals no shift or clunk throughout ROM, Grade 1 (trace) equals subtle shift barely palpable but not visible, Grade 2 (moderate) equals definite clunk felt clearly but not visible, Grade 3 (gross) equals obvious clunk both felt and visible ("jump sign" where lateral tibial plateau visibly reduces). INTERPRETATION: Grade 0-1 acceptable (near-normal rotational stability), Grade 2-3 unacceptable indicating inadequate rotational control requiring revision intra-operatively. CAUSES of positive post-op pivot shift: (1) Femoral tunnel TOO ANTERIOR (11-12 o'clock instead of 10-11 o'clock right knee) - most common cause (transtibial technique or poor AM portal technique creating vertical anterior graft with poor rotational restraint). MANAGEMENT: If identified before closing, may need to abandon femoral tunnel and re-drill posteriorly at 10-11 o'clock anatomic position (time-consuming and technically demanding intra-operatively but necessary for proper outcome). (2) Graft UNDER-TENSIONED (inadequate tension on tibial end during fixation creating slack graft). MANAGEMENT: Release tibial fixation and re-fix with increased tension. (3) Femoral fixation FAILURE (button not flipped, screw diverged, fixation pulling out). MANAGEMENT: Check femoral fixation integrity (pull on graft testing fixation security, palpate lateral femur for button, arthroscopically assess graft in femoral tunnel for motion), revise femoral fixation if failed. EVIDENCE: Residual positive pivot shift (grade 2-3) after ACL reconstruction predicts poor functional outcomes - studies show patients with grade 2-3 pivot shift post-op have 30-50 percent LOWER return to sport rates, 20-30 percent LOWER patient satisfaction scores, 15-25 percent HIGHER graft failure rates at 5 years compared to grade 0-1 pivot shift patients. Therefore, positive pivot shift intra-operatively requires revision to achieve negative test before closing (not acceptable to leave OR with grade 2-3 pivot shift). DOCUMENTATION IMPORTANCE: Operative note must comprehensively document final assessment findings (ROM achieved, stability tests results, arthroscopic inspection findings, any complications and management) for medical-legal protection and quality assurance. If complication occurs post-operatively, operative note provides evidence that thorough assessment performed intra-operatively and knee stable/full ROM before closing (helps defend against claims of technical error if note documents negative pivot shift and full extension achieved). EXAM QUESTION: What are consequences of missing 5 degrees extension loss before closing after ACL reconstruction and how do you prevent this? ANSWER: Five degrees extension loss causes quadriceps shutdown (neurologic inhibition reducing quadriceps strength 30-50 percent from inability to fully extend preventing normal quadriceps activation), patellofemoral pain (altered mechanics increasing contact stress 200-300 percent causing chronic anterior knee pain), patellofemoral arthritis (accelerated cartilage degeneration from abnormal loading), gait abnormality (limp from inability to fully extend in stance phase), and functional limitation (cannot run or perform sports normally). This is most common cause of patient dissatisfaction after ACL reconstruction and potential litigation from deviation from standard of care. Prevention requires systematic final assessment before closing: (1) Bring knee to full extension 0 degrees and confirm with goniometer (not 3-5 degrees - must be true 0), (2) Arthroscopically visualize graft in terminal extension confirming 2-3mm clearance from anterior roof and lateral wall without impingement, (3) Feel extension endpoint (firm bony endpoint indicates full extension, soft springy endpoint indicates mechanical block), (4) If extension loss present identify cause and correct before closing (perform or extend notchplasty for impingement, release and re-tension tibial fixation if over-constrained, debride residual ACL stump if cyclops, may need to re-drill femoral tunnel if too anterior), (5) Only proceed with closure after achieving full 0 degrees extension (non-negotiable checkpoint). Never accept extension loss planning for post-operative therapy (mechanical loss does not improve with therapy).' - MISSING EXTENSION LOSS before closing (most common missed complication) - surgeon closes without confirming full 0 degrees extension. CONSEQUENCE: Post-operative extension deficit (5-10 degrees flexion contracture persisting despite therapy), quadriceps shutdown (strength reduced 30-50 percent), patellofemoral pain and arthritis (accelerated degeneration), gait abnormality (limp), functional limitation (cannot return to sports), patient dissatisfaction (most common reason for dissatisfaction after ACL), possible litigation (deviation from standard of care). PREVENTION: Systematically check full extension before closing (bring knee to 0 degrees, measure with goniometer, arthroscopically visualize graft clearance from roof and walls, feel firm bony endpoint), if ANY extension loss present identify cause and correct intra-operatively before proceeding (notchplasty for impingement, release and re-tension fixation if over-constrained, debride cyclops lesion, possibly re-drill femoral tunnel if too anterior), never accept extension loss planning for post-op therapy (mechanical loss will not improve with therapy). - ACCEPTING POSITIVE PIVOT SHIFT before closing - surgeon feels grade 2-3 pivot shift but proceeds with closure assuming "will improve with rehab." CONSEQUENCE: Post-operative rotational instability (patient reports knee giving way with cutting or pivoting activities), functional limitation (cannot return to sports requiring pivoting like soccer, basketball, tennis), higher graft failure rate (15-25 percent increased failure risk with grade 2-3 pivot shift versus grade 0-1), patient dissatisfaction (30-50 percent lower return to sport rate). PREVENTION: Perform pivot shift test under adequate anesthesia (muscle relaxation essential for valid test), if grade 2-3 pivot shift present identify cause and correct before closing (femoral tunnel too anterior requires re-drilling posteriorly at 10-11 o'clock, graft under-tensioned requires release and re-fixation tibia with more tension, femoral fixation failure requires revision femoral fixation), only proceed when grade 0-1 pivot shift achieved (acceptable rotational stability). - GRAFT DAMAGE OR ABRASION from sharp tunnel edges missed during inspection - sharp bone spicules at tunnel apertures abrade graft fibers during ROM causing gradual graft weakening. CONSEQUENCE: Late graft failure (insidious graft elongation and eventual rupture 2-10 years post-op from repetitive abrasion at tunnel edges - most common cause of late failure), increased laxity over time (graft fibers progressively disrupted causing gradual translation increase), patient returns with instability years after initially successful reconstruction. PREVENTION: Arthroscopically inspect tibial and femoral tunnel apertures carefully before closing (look for sharp bone edges, corners, or spicules that could contact graft), smooth ALL edges with rasp or curette or burr creating beveled chamfered edges (30-45 degree bevel removing sharp corners), cycle knee through ROM while viewing graft at tunnel apertures (should see graft glide smoothly without snagging or catching on edges), if any sharp edges identified debride thoroughly until smooth. - UNRECOGNIZED FIXATION FAILURE - button not flipped, screw diverged, or fixation pulling out during final ROM check but not identified. CONSEQUENCE: Post-operative graft pullout (acute failure within days to weeks presenting as sudden instability, positive Lachman and pivot shift, inability to weight-bear), requires revision surgery acutely (re-fixation or revision reconstruction depending on timing and damage). PREVENTION: Test fixation security before closing (pull on graft with moderate force 20 pounds ensuring no pullout from femoral or tibial tunnels, palpate lateral femur confirming button flip and seating, arthroscopically visualize graft in tunnels during ROM confirming no excessive motion indicating fixation failure), if ANY concern about fixation integrity revise fixation before closing (re-flip button if not flipped, remove and re-insert screw if diverged, add backup tibial fixation if tibial screw questionable). - LOOSE BODIES OR DEBRIS left in joint - bone chips from tunnel drilling, graft fragments from preparation, meniscal or cartilage fragments from iatrogenic injury. CONSEQUENCE: Post-operative mechanical symptoms (clicking, catching, locking from loose body), synovitis and effusion (foreign material causes inflammation), need for repeat arthroscopy to remove debris (second surgery within weeks to months). PREVENTION: Irrigate joint copiously at end of case (3-5 liters saline minimum flushing all compartments thoroughly), arthroscopically inspect all compartments systematically before closing (medial gutter, lateral gutter, suprapatellar pouch, posterior compartments, intercondylar notch) looking for loose material, use motorized shaver or grasper to remove any debris identified, perform final sweep confirming joint clean. ### Step 12: Wound Closure and Dressing Wound Closure and Dressing: GOAL: Close all incisions with appropriate technique preventing infection, minimizing scarring, ensuring hemostasis. TOURNIQUET DEFLATION (if tourniquet used): Release tourniquet before closure allowing vascular reperfusion and identification of bleeding requiring cautery. Wait 5-10 minutes after deflation for blood pressure to equilibrate and identify arterial bleeders (small vessels may not bleed under tourniquet but bleed once tourniquet released). Use electrocautery to cauterize any bleeding vessels in subcutaneous tissues or capsule (bipolar cautery preferred near nerves to avoid thermal spread, monopolar cautery adequate for larger vessels). Achieve complete hemostasis before closure (no active bleeding visible minimizes post-operative hemarthrosis and hematoma formation). ANTERIOR TIBIAL INCISION CLOSURE (graft harvest site and tibial tunnel incision): Typically single 3-5cm longitudinal or oblique incision on anteromedial proximal tibia. DEEP LAYER closure (fascia/periosteum layer if violated): Close periosteum over tibial tunnel with interrupted absorbable sutures (2-0 or 3-0 Vicryl or Monocryl) reducing dead space and preventing soft tissue herniation into tunnel (periosteal closure not critical - many surgeons skip this layer). SUBCUTANEOUS LAYER: Close deep dermis/subcutaneous tissues with interrupted or running absorbable sutures (3-0 or 4-0 Vicryl or Monocryl) approximating skin edges and eliminating dead space (reduces hematoma risk and improves cosmesis). SKIN CLOSURE options: (1) SUBCUTICULAR running absorbable suture (4-0 or 5-0 Monocryl most common) - buried subcuticular stitch providing good cosmesis without need for suture removal (suture absorbs over 8-12 weeks by which time wound healed), (2) Non-absorbable interrupted or running sutures (4-0 or 5-0 nylon or Prolene) - traditional method requiring suture removal 10-14 days post-op, slightly higher tensile strength during healing but cosmesis equivalent to absorbable, (3) Skin staples - fastest closure technique (each staple takes 2-3 seconds) used commonly for speed especially in long cases, requires staple removal 10-14 days, cosmesis slightly inferior to suture (small puncture marks at each staple site), higher infection risk (staples create more tissue trauma than sutures), (4) Skin adhesive (Dermabond, surgical glue) - cyanoacrylate glue applied topically over approximated skin edges creating waterproof seal, no need for removal (glue peels off in 7-14 days as epidermis sheds), excellent cosmesis, but requires dry field (any bleeding prevents adhesion) and well-approximated edges (does not provide any closure force - only seals already-closed wound). PREFERENCE: Most surgeons use subcuticular absorbable suture for balance of cosmesis, strength, and convenience (no removal needed). STERI-STRIPS application: Apply adhesive strips perpendicular to incision over skin closure (whether sutured or glued) providing additional wound edge approximation and support (reduces tension on healing skin edges preventing dehiscence). Leave steri-strips in place 7-14 days (will peel off naturally or remove at first post-op visit). PORTAL CLOSURES (arthroscopic portals - anterolateral and anteromedial portals): Small 5-8mm incisions typically closed simply. OPTIONS: (1) Single interrupted absorbable suture (4-0 Monocryl) approximating skin edges sufficient for small portal, (2) Skin adhesive applied over portal without suture (adequate for 5mm portals if edges well-approximated), (3) Leave open (some surgeons leave portals open allowing drainage and close spontaneously - outdated practice higher infection risk, not recommended). MODERN STANDARD: Single suture or skin adhesive for all portals. LATERAL THIGH INCISION (if using suspensory femoral button fixation): Tiny 5-10mm incision over lateral femoral cortex where button deployed. Close with single interrupted absorbable suture (4-0 Monocryl) or skin adhesive. May leave lateral incision open if very small (less than 5mm) though suture closure preferred for infection prevention. DRAIN PLACEMENT decision: CONTROVERSIAL - no consensus. Options: (1) NO DRAIN - most common current practice (60-70 percent surgeons do not use drain), rationale: Modern arthroscopic technique with copious irrigation and good hemostasis creates minimal bleeding post-operatively making drain unnecessary, drains may increase infection risk by creating portal for bacterial entry, drains cause patient discomfort and limit mobility. Evidence: Multiple RCTs show no difference in hemarthrosis, pain, or outcomes with versus without drain in routine ACL reconstruction. (2) INTRA-ARTICULAR DRAIN placed through portal exiting joint and brought out through skin (10-12 Fr suction drain like Hemovac or Blake drain) - used by some surgeons especially if hemostasis suboptimal or patient on anticoagulation. Remove drain 24 hours post-op. (3) DRAIN OVER TIBIAL TUNNEL in subcutaneous plane (not intra-articular) preventing hematoma at tibial incision. CURRENT RECOMMENDATION: No drain for routine primary ACL reconstruction in healthy patient with good hemostasis (drain not beneficial and potentially harmful). Consider drain if: patient on anticoagulation (higher bleeding risk), revision ACL with extensive dissection (more bleeding expected), hemostasis suboptimal at end of case despite cautery (persistent oozing). DRESSING APPLICATION: STERILE TECHNIQUE throughout. FIRST LAYER (contact layer): Apply sterile non-adherent dressing directly on incisions (Telfa or Adaptic non-stick pad prevents dressing from adhering to wound allowing painless dressing changes). SECOND LAYER (absorbent layer): Apply sterile gauze pads (4x4 inch gauze) over non-adherent layer absorbing any drainage or bleeding (typically 4-8 gauze pads covering anterior knee including portal sites, tibial incision, and lateral thigh if present). COMPRESSION LAYER: Apply elastic bandage wrap (Ace wrap or Coban) over gauze with MODERATE circumferential compression (gentle compression reduces post-operative swelling and hemarthrosis without causing vascular compromise or compartment syndrome). Start wrap at ankle and spiral proximally to mid-thigh covering entire knee and calf. Ensure compression not excessive (should be able to insert 1-2 fingers under wrap edge indicating adequate perfusion). IMMOBILIZATION decision: (1) NO BRACE (unlocked ROM allowed immediately) - increasingly common modern approach for hamstring autograft ACL reconstruction (40-50 percent surgeons), rationale: Strong fixation allows immediate ROM without protection, early motion prevents stiffness and improves outcomes, no evidence that bracing improves stability or reduces failure rates. (2) HINGED KNEE BRACE locked in extension 0 degrees - traditional approach still used by many surgeons (50-60 percent), rationale: Protects reconstruction during early healing phase preventing excessive stress on graft, prevents flexion contracture by maintaining full extension, provides patient psychological confidence (feels protected). BRACE PROTOCOL if using: Locked in extension 0 degrees for first 24-48 hours (ensures extension maintained while nerve block wearing off and pain high), then unlock brace allowing 0-90 degrees ROM for weeks 1-2 (protected motion preventing hyperextension or excessive flexion), advance ROM in brace to 0-120 degrees weeks 3-4, discontinue brace weeks 4-6 once quadriceps control adequate and extension stable. EVIDENCE: Multiple Level 1 RCTs comparing bracing versus no bracing show no difference in outcomes (ROM, strength, stability, return to sport all equivalent). CONCLUSION: Bracing optional based on surgeon preference and patient factors (unlocked ROM allowed with strong fixation in compliant patient, consider brace for large patient, heavy manual labor occupation, or patient with poor compliance where protection beneficial). CRYOTHERAPY (ice therapy): Apply ice over dressing for first 24-72 hours post-op for pain control and edema reduction (ice reduces metabolic demand, vasoconstriction decreases bleeding and swelling, analgesic effect). Can use ice bags, cold therapy device (Cryocuff, Game Ready), or ice machine with circumferential wrap. Apply 20 minutes every 2-3 hours while awake for first 2-3 days. ELEVATION: Elevate operative leg above heart level for first 24-48 hours reducing venous pooling and edema (prop leg on pillows with ankle above heart, not just foot on stool which insufficient elevation). FINAL INSTRUCTIONS before patient leaves OR: Document and communicate to recovery room nurses and patient/family: (1) Weight-bearing status (typically weight-bearing as tolerated with crutches for comfort, full weight-bearing allowed if no meniscal repair), (2) ROM restrictions (none if unlocked, or 0-90 degrees if braced), (3) Dressing instructions (keep dressing clean and dry for 48-72 hours, may shower after 72 hours with waterproof covering, remove outer wrap at 48 hours leaving sterile gauze on incisions), (4) Pain management (prescribed opioid analgesics for 3-5 days post-op, transition to acetaminophen or NSAIDs, ice therapy), (5) DVT prophylaxis (early mobilization, ankle pumps, consider aspirin 325mg daily for 14 days in high-risk patient), (6) Follow-up appointment (typically 7-14 days post-op for wound check and early rehab assessment), (7) Warning signs requiring urgent contact (fever greater than 38.5C indicating possible infection, excessive swelling or pain out of proportion indicating compartment syndrome, loss of distal pulses or foot numbness indicating vascular or nerve injury, wound drainage or erythema suggesting infection, inability to straight leg raise indicating quadriceps rupture). **Technical Tip**: EXAM KEY: 'WOUND CLOSURE technique important for cosmesis and infection prevention. SUBCUTICULAR ABSORBABLE SUTURE technique preferred by most surgeons (buried running subcuticular stitch using 4-0 or 5-0 Monocryl or Vicryl Rapide) provides excellent cosmesis (no visible suture marks or track marks from percutaneous sutures), eliminates need for suture removal (patient convenience - no return visit just for suture removal), adequate tensile strength during healing (absorbable sutures maintain strength for 2-4 weeks sufficient for skin healing which achieves 50 percent final strength by 2 weeks, 80 percent by 4 weeks). TECHNIQUE: Insert needle in subcuticular plane (layer between dermis and subcutaneous fat - NOT through epidermis which creates visible track marks), run suture horizontally taking small bites alternating sides creating mattress pattern, bury knot at both ends subcuticularly (start and end knots under skin so no visible knot). ALTERNATIVE CLOSURES: Interrupted non-absorbable sutures (4-0 nylon or Prolene) provide slightly higher tensile strength (non-absorbable maintains strength indefinitely versus absorbable starts losing strength at 2 weeks) but requires suture removal 10-14 days (patient must return, removal sometimes painful, track marks can occur if sutures left longer than 14 days creating permanent scars). Staples fastest technique (useful in long cases where time critical) but inferior cosmesis (each staple creates small puncture mark, linear array of dots remains visible) and higher infection risk (staples cause more tissue trauma than sutures damaging local blood supply and creating bacterial entry points - infection rate 2-3 percent with staples versus 1 percent with sutures). Skin adhesive (Dermabond surgical glue) excellent cosmesis (no sutures visible, waterproof seal allows immediate showering) but requires perfectly dry field (any bleeding prevents glue adhesion causing dehiscence) and provides no closure force (glue only seals already-approximated edges - cannot pull apart edges). PREFERENCE for ACL incisions: Subcuticular absorbable suture BEST option balancing cosmesis, strength, convenience. DRAIN USE CONTROVERSY: Historic practice placed intra-articular drain routinely after ACL reconstruction (hemovac or Blake drain through arthroscopic portal exiting joint and brought out skin connected to suction bulb) to evacuate hemarthrosis (blood in joint). RATIONALE for drain: Reduce post-op hemarthrosis (blood in joint causes pain, stiffness, limits motion, inhibits quadriceps - "arthogenic muscle inhibition"), prevent hematoma formation (hematoma can cause compartment syndrome or compression of neurovascular structures), facilitate early ROM (less swelling theoretically allows easier motion). MODERN EVIDENCE questioning drain necessity: Multiple Level 1 RCTs published 2000s-2010s comparing drain versus no drain in ACL reconstruction show NO significant difference in any outcome measure: Hemarthrosis volume (measured by aspiration or MRI) equivalent between groups (drain does not significantly reduce post-op blood accumulation versus modern arthroscopic technique with good hemostasis and irrigation), Pain scores VAS equivalent, ROM at 2 weeks, 6 weeks, 3 months equivalent (no advantage to drain for motion recovery), Quadriceps strength recovery equivalent, Infection rate actually HIGHER with drain (2-3 percent versus 1 percent without drain - drain creates portal for bacterial entry contaminating joint), Patient satisfaction lower with drain (drain uncomfortable and limits mobility). REASONS drains not beneficial: (1) Modern arthroscopic ACL technique has MINIMAL bleeding (meticulous hemostasis with cautery, copious irrigation flushing blood and debris, tourniquet use during graft harvest) creating little post-op bleeding making drain unnecessary. Historic open ACL techniques with larger dissection and more bleeding benefited from drainage but modern arthroscopic approach different. (2) Drains REMOVE beneficial substances along with blood (drain evacuates not only blood but also growth factors, cytokines, and healing mediators in blood and joint fluid that promote graft healing - removing these may impair healing). (3) Drain creates INFECTION RISK (retrograde bacterial entry through drain tract colonizing joint). CURRENT PRACTICE: Most surgeons do NOT use drain for routine primary ACL reconstruction (60-70 percent no drain based on surveys). Selective drain use if: Patient on anticoagulation (warfarin, heparin, DOAC) with higher bleeding risk, revision ACL with extensive dissection and more bleeding expected, hemostasis suboptimal at end of case (persistent oozing despite cautery warrants drain for safety), combined procedures with meniscal repair or cartilage restoration (more bleeding). BRACE USE DEBATE similar to drain controversy: Historic practice braced all ACL reconstructions locked in extension for 4-6 weeks protecting graft. MODERN TREND toward no brace (immediate unlocked ROM) based on evidence: Multiple RCTs show no difference in outcomes with versus without post-op bracing (ROM, strength, stability, graft failure rate all equivalent at 1-2 years), early motion BENEFICIAL (prevents stiffness, facilitates quadriceps recovery, improves patient satisfaction - "motion is lotion"), modern fixation techniques (button and interference screw) provide STRONG fixation (800-1200N pullout strength exceeding forces during early rehab 200-600N making brace unnecessary for graft protection). CURRENT PRACTICE: Approximately 50-50 split between surgeons using brace versus no brace (personal preference rather than evidence-based). Arguments FOR brace: Protects graft during nerve block wearing off when patient has limited proprioception (prevents hyperextension or excessive flexion from uncontrolled movements), maintains full extension preventing flexion contracture (locked 0 degrees overnight ensures extension maintained), provides patient psychological confidence (feels protected enhancing compliance with rehab). Arguments AGAINST brace: No proven benefit for graft protection or outcomes (evidence shows equivalent results without brace), added cost (brace costs 200-500 dollars), patient discomfort (bulky brace during sleep and daily activities), possible increased stiffness if brace limits motion. RECOMMENDATION: Brace optional based on surgeon preference. Reasonable to avoid brace in low-risk patient (young, compliant, strong fixation, no meniscal repair) allowing immediate unlocked ROM. Consider brace in high-risk patient (heavy, manual labor, poor compliance, meniscal repair requiring protection, weak bone quality with fixation concern). EXAM QUESTION: Summarize evidence regarding intra-articular drain use and post-operative bracing after ACL reconstruction. ANSWER: Multiple Level 1 RCTs published since 2000 comparing drain versus no drain show no benefit to routine drain use: Hemarthrosis volume, pain scores, ROM, quadriceps recovery all equivalent between groups. Drains actually associated with higher infection risk (2-3 percent versus 1 percent without drain from retrograde bacterial contamination through drain tract) and patient discomfort. Modern arthroscopic ACL technique with meticulous hemostasis and irrigation creates minimal post-operative bleeding making drain unnecessary in most cases. Current recommendation: No drain for routine primary ACL reconstruction, consider drain only if patient on anticoagulation with high bleeding risk, revision with extensive dissection, or hemostasis suboptimal at closure. Similarly, multiple RCTs comparing bracing versus no bracing show no difference in any outcome (ROM, strength, stability, graft failure rates equivalent at 1-2 years). Early motion without brace beneficial for preventing stiffness and facilitating quadriceps recovery. Modern strong fixation (800-1200N) exceeds early rehab forces (200-600N) making brace unnecessary for graft protection. Current practice: Approximately 50 percent surgeons brace and 50 percent no brace based on preference - no evidence supporting routine bracing. Reasonable to avoid brace in low-risk patient allowing immediate ROM, consider brace in high-risk patient for protection and compliance.' - COMPARTMENT SYNDROME from excessive compressive dressing (rare but catastrophic 0.1-0.5 percent) - tight circumferential wrap or brace creates external compression increasing intra-compartment pressures above perfusion pressure causing muscle and nerve ischemia. CONSEQUENCE: Muscle necrosis (permanent damage to compartment muscles - anterior compartment syndrome affects tibialis anterior, extensor hallucis longus, extensor digitorum longus causing permanent foot drop and toe extension weakness; deep posterior compartment syndrome affects tibialis posterior, flexor hallucis longus, flexor digitorum longus causing permanent plantar flexion weakness), nerve injury (permanent sensory deficit and possible neuropathic pain from deep peroneal nerve or tibial nerve damage), limb-threatening ischemia (complete muscle death can progress to rhabdomyolysis, acute kidney injury from myoglobin, systemic toxicity, possible amputation if not recognized and treated within 6-8 hours from onset). RECOGNITION: Post-operative signs of compartment syndrome (5 Ps): Pain out of proportion to expected post-op pain (severe unrelenting pain not controlled by opioid analgesics - most sensitive early sign), Pain with passive stretch (passive toe or ankle dorsiflexion causes severe calf or anterior leg pain - specific sign indicating muscle ischemia), Paresthesias (numbness or tingling in foot or toes from nerve ischemia - deep peroneal nerve causes first web space numbness, tibial nerve causes plantar foot numbness), Pallor (pale or mottled skin from vascular compromise - late sign), Pulselessness (absent dorsalis pedis or posterior tibial pulse - very late sign indicating critical ischemia, often compartment syndrome already caused irreversible damage by time pulses lost). Compartment pressure measurement: Use handheld pressure monitor (Stryker device or arterial line transducer with needle in compartment) measuring intra-compartment pressure - normal less than 10-15 mmHg, elevated 20-30 mmHg, compartment syndrome pressures greater than 30 mmHg or within 30 mmHg of diastolic blood pressure (Delta P equals diastolic BP minus compartment pressure, if Delta P less than 30 mmHg indicates inadequate perfusion pressure requiring fasciotomy). MANAGEMENT: If compartment syndrome suspected (pain out of proportion, pain with passive stretch, elevated pressures), IMMEDIATE FASCIOTOMY (emergency surgical decompression of all four leg compartments - anterior, lateral, deep posterior, superficial posterior - through two longitudinal incisions releasing fascia allowing muscle expansion and restoring perfusion). Delay beyond 6-8 hours from onset causes IRREVERSIBLE muscle and nerve damage (even if fasciotomy performed damage already permanent). PREVENTION: (1) Apply compression dressing with MODERATE tension only (should be able to insert 1-2 fingers under wrap edge confirming adequate perfusion, avoid circumferential tight wrapping especially around calf), (2) If using brace ensure brace not overtightened (straps snug but not constricting, check skin color and capillary refill distal to brace - should be pink with less than 2 second capillary refill), (3) Educate patient and nurses about warning signs (instruct patient to loosen dressing or brace if pain severe or numbness develops, nurses should check neurovascular status every 2-4 hours first 24 hours post-op documenting pulses, sensation, motor function, compartment palpation for tension), (4) Avoid combining circumferential compressive dressing with locked brace (dual compression increases risk - if using brace leave dressing non-circumferential with wrap open posteriorly). HIGH-RISK patients for compartment syndrome: Hemophilia or coagulopathy (increased bleeding into compartments), anticoagulation medication (warfarin, heparin, DOAC increases bleeding risk), revision surgery with extensive dissection (more bleeding and trauma), prolonged tourniquet time greater than 2 hours (tourniquet ischemia causes reperfusion injury and edema when deflated increasing compartment pressures). - WOUND INFECTION from inadequate sterile technique or contamination - post-operative surgical site infection (SSI) developing days to weeks post-op. INCIDENCE: Approximately 0.5-2 percent of ACL reconstructions develop SSI (low rate but serious complication). RISK FACTORS: Diabetes (hyperglycemia impairs wound healing and immune function), obesity (BMI greater than 30 increases infection risk 2-3 fold from increased adipose tissue and altered vascularity), smoking (nicotine causes vasoconstriction reducing tissue oxygen and impairing healing), prolonged operative time (each additional hour increases infection risk 10-20 percent from prolonged tissue exposure), contamination during surgery (graft drops on floor, break in sterile technique). TYPES of infection: (1) SUPERFICIAL incisional SSI (skin and subcutaneous tissues only, not involving deeper structures) - presents within 7-14 days with incision erythema, purulent drainage, wound dehiscence. Managed with wound opening, irrigation, antibiotics (oral cephalexin or clindamycin for 7-10 days), dressing changes until healing by secondary intention. Usually does NOT affect graft (graft separated from skin by multiple tissue layers). (2) DEEP incisional SSI (involves muscle, fascia, or deeper structures but not joint) - presents with deep tenderness, fluctuance, fever, elevated inflammatory markers CRP/ESR. Requires surgical debridement (open and irrigate deep tissues, remove non-viable tissue), culture (guide antibiotic choice), IV antibiotics for 2-4 weeks, possible graft retention if not involved. (3) INTRA-ARTICULAR infection (septic arthritis involving joint and graft - most serious) - presents with severe pain, large effusion, inability to weight-bear, fever, systemic symptoms. DEVASTATING complication: Septic arthritis after ACL causes rapid cartilage destruction (bacterial enzymes and inflammatory mediators degrade articular cartilage within days causing permanent arthritis), graft failure (infection prevents graft healing and incorporation leading to graft necrosis), possible chronic osteomyelitis. Requires URGENT surgical management: Arthroscopic or open irrigation and debridement (wash out joint thoroughly removing purulent material and necrotic tissue), graft removal (infected graft cannot be salvaged - acts as nidus for persistent infection - must explant graft), culture (aerobic, anaerobic, fungal cultures to identify organism), IV antibiotics for 4-6 weeks (based on cultures and sensitivities - typical organisms: Staphylococcus aureus 50 percent including MRSA 15-20 percent, coagulase-negative Staph 20 percent, Streptococcus 10 percent, gram-negative rods 10 percent), staged revision ACL reconstruction after infection cleared (minimum 6-12 months delay allowing infection eradication and inflammation resolution before re-reconstruction). PREVENTION: (1) Pre-operative skin preparation (chlorhexidine or betadine scrub for 5 minutes prepping entire leg from hip to toes), (2) Prophylactic IV antibiotics within 60 minutes before incision (cefazolin 2 grams IV most common, or clindamycin/vancomycin if penicillin allergy or MRSA risk), (3) Maintain strict sterile technique throughout case (sterile draping, double gloving, minimize personnel traffic, avoid touching graft with contaminated surfaces), (4) Copious irrigation before closure (3-5 liters saline flushing joint and wounds removing bacteria and debris), (5) Minimize operative time (complete case within 2 hours if possible reducing tissue exposure and bacterial contamination time). - NERVE INJURY from suture needle or cautery during closure - iatrogenic injury to subcutaneous sensory nerves (infrapatellar branch of saphenous nerve most common, superficial peroneal nerve if lateral dissection). CONSEQUENCE: Permanent numbness anterior knee (infrapatellar nerve injury causes numb patch 5-10 cm diameter on anterior knee/proximal medial leg - very common 20-30 percent of ACL patients have some degree of numbness from nerve injury), hyperesthesia or dysesthesia (hypersensitivity or unpleasant sensation from partial nerve injury - less common 5 percent but more bothersome to patient than simple numbness), painful neuroma formation (rare 1-2 percent - if nerve transected can form bulbous neuroma at cut end causing point tenderness and shooting pain with palpation). Usually NOT functionally significant (pure sensory nerve no motor function affected) but cosmetically and psychologically bothersome to some patients. PREVENTION: Careful subcutaneous dissection (blunt dissection spreading with hemostat rather than cutting blindly reduces nerve injury risk), identify and protect saphenous nerve and infrapatellar branch if visualized during anterior tibial incision (retract gently rather than transecting), use cautery carefully (avoid excessive thermal spread near visible nerves - use bipolar cautery for precision near nerves). If numbness occurs post-operatively (common), counsel patient that sensation may recover partially over 6-12 months (70-80 percent improve though rarely returns to completely normal), usually not bothersome long-term. If painful neuroma develops (rare), management options: Conservative (observation, desensitization therapy, topical analgesics - lidocaine patches), nerve blocks (local anesthetic or steroid injection at neuroma site providing temporary relief), surgical excision (remove neuroma and bury nerve end in muscle to prevent reformation - success rate 70-80 percent for pain relief). **Phase 1 (0-2 weeks)**: Goals - control swelling, achieve full extension (0°), flexion to 90°, quadriceps activation. Weight-bearing as tolerated with crutches, unlock brace for exercises. Exercises: quadriceps sets hourly, straight leg raise when quad control adequate, heel slides, patellar mobilization, prone hangs for extension. Cryotherapy and elevation. No active hamstring exercises yet to protect healing graft. **Phase 2 (2-6 weeks)**: Goals - full ROM (0-130°), normalize gait, progress strengthening. Wean crutches and brace. Closed-chain exercises: wall sits, mini squats 0-60°, step-ups. Begin cycling (high seat, low resistance). Pool walking week 4. Proprioception training: single-leg balance, wobble board. Continue quad emphasis. **Phase 3 (6-12 weeks)**: Goals - normalize strength, functional activities. Full ROM maintained. Progress squats to 90°, lunges, step-downs. Begin open-chain quads week 8-12. Begin hamstring strengthening week 8. Swimming. Advanced proprioception with perturbation training. **Phase 4 (12-24 weeks)**: Goals - running program, sport-specific training. Straight-line running progression starting week 12-16. Plyometrics: double-leg then single-leg jumping. Agility drills: cutting, figure-8. Sport-specific drills. Isokinetic testing at 4 months. **Phase 5 (6-12 months)**: Return to sport when ALL criteria met: minimum 9 months, quad/hamstring LSI greater than 90%, hop testing LSI greater than 90%, full ROM, no effusion/pain, psychological readiness (ACL-RSI greater than 56), sport-specific training complete. Progressive RTS: non-contact training, limited contact, full practice, competition. Optimal RTS 12 months for elite athletes. ## References 1. Getelman MH, Friedman MJ. Revision anterior cruciate ligament reconstruction surgery. J Am Acad Orthop Surg. 1999;7(3):189-198. doi:10.5435/00124635-199905000-00005 2. Magnussen RA, Lawrence JTR, West RL, Toth AP, Taylor DC, Garrett WE. Graft size and patient age are predictors of early revision after anterior cruciate ligament reconstruction with hamstring autograft. Arthroscopy. 2012;28(4):526-531. doi:10.1016/j.arthro.2011.11.024 3. Snaebjörnsson T, Hamrin Senorski E, Ayeni OR, et al. Graft diameter as a predictor for revision anterior cruciate ligament reconstruction and KOOS and EQ-5D values: A cohort study from the Swedish National Knee Ligament Register Based on 2240 patients. Am J Sports Med. 2017;45(9):2092-2097. doi:10.1177/0363546517704177 4. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. Br J Sports Med. 2016;50(13):804-808. doi:10.1136/bjsports-2016-096031 5. Webster KE, Feller JA, Leigh WB, Richmond AK. Younger patients are at increased risk for graft rupture and contralateral injury after anterior cruciate ligament reconstruction. Am J Sports Med. 2014;42(3):641-647. doi:10.1177/0363546513517540 6. Lind M, Menhert F, Pedersen AB. The first results from the Danish ACL reconstruction registry: epidemiologic and 2 year follow-up results from 5,818 knee ligament reconstructions. Knee Surg Sports Traumatol Arthrosc. 2009;17(2):117-124. doi:10.1007/s00167-008-0654-3 7. Maletis GB, Inacio MC, Funahashi TT. Analysis of 16,192 anterior cruciate ligament reconstructions from a community-based registry. Am J Sports Med. 2013;41(9):2090-2098. doi:10.1177/0363546513493573 8. Prodromos CC, Han Y, Rogowski J, Joyce B, Shi K. A meta-analysis of the incidence of anterior cruciate ligament tears as a function of gender, sport, and a knee injury-reduction regimen. Arthroscopy. 2007;23(12):1320-1325.e6. doi:10.1016/j.arthro.2007.07.003 9. Ardern CL, Webster KE, Taylor NF, Feller JA. Return to sport following anterior cruciate ligament reconstruction surgery: a systematic review and meta-analysis of the state of play. Br J Sports Med. 2011;45(7):596-606. doi:10.1136/bjsm.2010.076364 10. Mohtadi NG, Chan DS, Dainty KN, Whelan DB. Patellar tendon versus hamstring tendon autograft for anterior cruciate ligament rupture in adults. Cochrane Database Syst Rev. 2011;(9):CD005960. doi:10.1002/14651858.CD005960.pub2

Arthroscopic ACL Reconstruction - Hamstring Autograft (Anatomic AM Portal Technique)

Arthroscopic ACL Reconstruction - Hamstring Autograft (Anatomic AM Portal Technique)