High Yield Overview

ACL RECONSTRUCTION - HAMSTRING AUTOGRAFT (4-STRAND)

Arthroscopic via anterolateral viewing portal and anteromedial working portal. Separate 3-4cm oblique incision over pes anserinus for hamstring harvest. | intermediate

Critical Danger Structures

Popliteal Artery

Location: 1cm posterior to posterior capsule and PCL at level of joint line, exits popliteal fossa through soleus arch

Protection: Never drill blindly posteriorly; guide pin must be controlled during femoral/tibial drilling; maintain hyperflexion during femoral reaming; place finger posterior to tibia during tibial reaming to feel for penetration

Saphenous Nerve

Location: Exits subsartorial canal 8-10cm proximal to medial joint line, runs 2-3cm medial to pes anserinus insertion deep to sartorius fascia alongside great saphenous vein

Protection: Make incision centered over pes anserinus (3cm distal, 2cm medial to tibial tubercle); stay superficial to sartorius fascia; avoid excessive medial retraction; injury causes medial leg/foot numbness in 5-10%

Infrapatellar Branch Saphenous Nerve

Location: Crosses superficially 1-2cm below medial joint line from posterior to anterior, supplies sensation to anterior knee and proximal medial leg

Protection: Unavoidable injury with anteromedial portal (occurs 50-70%); counsel patient pre-operatively about numbness; make smallest portal possible; consider high anteromedial portal to reduce area of numbness

Posterior Cruciate Ligament

Location: Inserts on posterior tibia 1cm distal to joint line, forms posterior wall of intercondylar notch, femoral attachment on medial wall of lateral femoral condyle

Protection: During notch debridement stay anterior to PCL fibers; during tibial reaming maintain guide pin lateral to medial tibial spine; avoid excessive posterior tibial tunnel placement; injury causes posterior laxity

Medial Femoral Condyle Articular Cartilage

Location: Hyaline cartilage surface of medial femoral condyle adjacent to intercondylar notch, at risk during trans-AM portal femoral drilling

Protection: Maintain knee flexion 110-120° during femoral drilling to position lateral wall anteriorly; ensure drill angle doesn't diverge medially; protect with careful reamer insertion; iatrogenic damage causes pain and arthritis

Mnemonic

HARVESTHARVEST - Hamstring Graft Technique

Mnemonic

TUNNELTUNNEL - Anatomic Tunnel Positioning

ACL Reconstruction Classification Systems

By Graft Type

Autograft (own tissue): Hamstring (ST/G), BPTB, Quadriceps tendon, Iliotibial band
Allograft (donor tissue): Higher infection rate (3-fold), slower incorporation, lower cost upfront but higher failure in young active patients
Synthetic grafts: Historical interest only, unacceptable failure rates, not recommended

By Bundle Technique

Single-bundle anatomic: Current gold standard - reproduces center of native ACL footprint, controls anterior translation and rotation
Double-bundle: Attempts to reconstruct AM and PL bundles separately - technically demanding, no proven superiority in RCTs, not widely adopted
Anatomic vs Non-anatomic single: Anatomic (via trans-AM portal) superior to transtibial technique which is now obsolete

By Fixation Strategy

Femoral Fixation Options:

Suspensory cortical: Endobutton, TightRope, ZipLoop - highest initial strength (>1000N), allows tensioning, graft-tunnel motion concerns (windshield wiper effect)
Interference screw: Aperture fixation, 7-9mm diameter, bioabsorbable preferred, requires good bone quality, risk of graft laceration
Cross-pins: TransFix, Rigid-Fix - excellent strength, technically demanding, less commonly used, risk of graft damage
Hybrid fixation: Suspensory plus interference screw - combines cortical strength with aperture fixation, increasingly popular

Tibial Fixation Options:

Interference screw: Most common, 7-9mm bioabsorbable, aperture fixation promotes graft-bone healing
Post fixation: Screw and soft tissue washer, backup fixation, risk of prominence
Suspensory: Less common at tibia, allows adjustment

By Surgical Timing

Acute (<3 weeks): Higher stiffness risk, recommend waiting for resolution of effusion and ROM recovery
Subacute (3-6 weeks): Optimal timing in most cases - inflammation resolved, ROM recovered
Chronic (>6 weeks): Standard risk profile, may have secondary meniscal tears or cartilage damage

Key Evidence Base

Landmark Studies

KANON Trial (2013): RCT of early ACL reconstruction vs rehab plus optional delayed reconstruction - 51% crossed over to surgery at 2 years, 61% at 5 years - supports early reconstruction in active patients
MOON Cohort (ongoing): Largest prospective ACL database - identified risk factors for revision: age <20 years (HR 2.4), BMI <25 (HR 1.9), graft diameter <8mm (HR 2.8)
Danish ACL Registry (2015): 15,783 reconstructions - hamstring revision rate 5.8% at 10 years vs BPTB 3.7% - higher in young males, but anterior knee pain lower (10% vs 30%)
Cochrane Review (2011): Hamstring vs BPTB - equivalent objective stability, BPTB better for kneeling symptoms, hamstring better for anterior knee pain

Australian Context

AOANJRR ACL Supplementary Report (2024): Most recent Australian data not yet available (registry started collecting ACL data 2018)
Medicare MBS items: 49560 (reconstruction primary) $1,183.80, 49561 (revision) $1,479.75
PBS: No specific medications (general perioperative antibiotics per hospital formulary)

Positioning and Preparation

Patient Position: Supine with commercial leg holder (or lateral post at thigh). Tourniquet on thigh (optional - I avoid routine use to reduce VTE risk and improve visualization with normal perfusion). Ensure full ROM before draping: passive extension to 0° and flexion >120°. Hip flexed 30-45° and externally rotated to relax hamstrings during harvest. Foot of bed dropped to allow knee hyperflexion 110-120° for femoral tunnel drilling.

Surgical Approach: Arthroscopic via anterolateral viewing portal and anteromedial working portal. Separate 3-4cm oblique incision over pes anserinus for hamstring harvest.

Incision: Portal incisions: 5mm stab incisions at joint line - anterolateral 1cm lateral to patellar tendon; anteromedial adjacent to medial border patellar tendon (high AM portal option to reduce saphenous nerve injury). Harvest incision: 3-4cm oblique over pes anserinus (3cm distal and 2cm medial to tibial tubercle) - this position minimizes saphenous nerve injury.

Equipment Setup: 30° arthroscope standard (70° optional for posterior compartment), 4.5mm arthroscopic shaver, arthroscopic graspers, ACL guide system (55° tibial guide), flexible reamers, closed-end tendon stripper, graft preparation board, sizing cylinders 6-12mm.

Operative Technique

Step 1: Examination Under Anaesthesia

Examination Under Anaesthesia: Perform systematic examination bilaterally. Grade: Lachman (flex 20-30°, measure anterior translation in mm, grade endpoint soft vs firm), anterior drawer (90° flexion, less sensitive than Lachman), pivot shift (grade 0-3, most specific test for functional instability). Assess varus/valgus stability at 0° and 30° to exclude collateral injury (>5mm opening indicates grade III injury). Check posterior drawer to exclude PCL injury. Document range of motion actively and passively. Compare to contralateral normal knee. Record findings for operative note and medicolegal documentation.

Exam Pearl

Technical Tip: EXAM KEY: 'I perform EUA to confirm diagnosis and grade instability. I test Lachman which is most sensitive (85% sensitivity), and pivot shift which is most specific for functional instability. A positive pivot shift (grade 2-3) indicates true functional instability and strongly supports reconstruction. I also check for concurrent ligamentous injuries - 20-30% have associated collateral or posterolateral corner injuries requiring staged or combined treatment.'

Dangers at this step

Missed multi-ligamentous injury - always test collaterals at 0° and 30° and posterolateral corner (dial test), failure to diagnose changes surgical planning
Inadequate documentation - record measurements and grades for medicolegal purposes, exam findings guide surgical plan
Excessive force during pivot shift testing - can worsen chondral injury especially if acute ACL with bone bruising, gentle technique required
Not comparing to contralateral side - bilateral ACL injury occurs in 0.5-1%, need baseline comparison

Step 2: Hamstring Graft Harvest

Hamstring Graft Harvest: 3-4cm oblique incision over pes anserinus (3cm distal, 2cm medial to tibial tubercle) - this position centered over pes insertion minimizes saphenous nerve injury. Incise sartorial fascia longitudinally in line with fibers. Palpate gracilis (most superior tendon, thin ribbon-like) and semitendinosus (inferior to gracilis, thicker cordlike) at tibial insertion. Clear tendon origin from tibia using finger dissection creating space around each tendon. Insert closed-end tendon stripper over each tendon sequentially. Strip tendons with firm steady pull - if significant resistance met, indicates accessory bands which must be released sharply with scissors or knife to prevent premature amputation. Aim for >28cm length each tendon (allows 7cm per limb after folding for adequate whipstitch and tunnel length). Check for premature amputation by inspecting tendon end - should be intact muscle belly not torn mid-substance.

Exam Pearl

Technical Tip: EXAM KEY: 'I harvest gracilis and semitendinosus via oblique incision centered over pes anserinus. The gracilis is superior and thin, semitendinosus inferior and thicker. I use closed tendon stripper and always release any accessory bands sharply if resistance is met - forced stripping causes premature amputation occurring in 10-15% which shortens graft length. I aim for >28cm length of each tendon to achieve adequate 4-strand graft of 8-10mm diameter with sufficient whipstitch length.'

Dangers at this step

Saphenous nerve injury - runs 2-3cm medial to incision deep to sartorius, stay superficial to sartorial fascia and avoid excessive medial dissection, injury rate 5-10% causing medial leg numbness
Graft amputation from accessory bands - occurs in 10-15% if bands not released, results in short inadequate graft length requiring alternative graft or proceeding with suboptimal construct
Inadequate graft length <24cm - makes 4-strand graft difficult or impossible, may need to accept smaller diameter or use alternative graft source
Semitendinosus artery avulsion - branch from superior medial genicular artery, can cause significant bleeding requiring cautery or ligation, rarely problematic but impairs visualization

Step 3: Graft Preparation

Graft Preparation: Clean all muscle from tendons using moist gauze or scalpel, removing every strand of muscle to leave just tendon. Whipstitch each tendon end with #2 high-strength non-absorbable suture (Ethibond or FiberWire) using Krackow locking technique with minimum 2.5cm whipstitch length to prevent pull-out. Fold each tendon at midpoint to create 4-strand construct with two whipstitched ends. Measure diameter using sizing cylinder - target 8-10mm diameter (>8mm mandatory for acceptable outcomes, <8mm has 2-3x higher failure rate especially in young active males). Place graft on tensioning device at 20-30 pounds tension. Leave to pretension during diagnostic arthroscopy for minimum 10 minutes to allow graft creep and settling. Mark graft length to ensure adequate length in each tunnel.

Exam Pearl

Technical Tip: EXAM KEY: 'I prepare a 4-strand graft by folding both tendons at their midpoint and whipstitching each end with high-strength suture using Krackow locking technique for minimum 2.5cm length. I pretension at 20-30 pounds on graft preparation board which allows the graft to undergo initial creep before implantation. Graft diameter ≥8mm is absolutely critical - diameters <8mm have 2-3x higher failure rate especially in young males. If I cannot achieve 8mm, I consider quadriceps tendon or BPTB as alternative graft source.'

Dangers at this step

Graft diameter <8mm - failure rate increases significantly to 10-20% especially in young males <25 years, consider alternative graft if cannot achieve adequate diameter
Inadequate whipstitch length <2cm - leads to graft slippage during tensioning and fixation causing construct failure, minimum 2.5cm required
Inadequate pretensioning time - leads to significant graft creep and laxity in first few weeks, minimum 10 minutes at 20-30 pounds recommended
Graft desiccation during preparation - keep constantly moist with saline-soaked gauze, dried graft has reduced strength and viability

Step 4: Portal Creation & Diagnostic Arthroscopy

Portal Creation & Diagnostic Arthroscopy: Inflate joint with 30-60ml saline via superolateral patellar approach using 18G needle to distend capsule. Anterolateral viewing portal: 5mm incision 1cm lateral to patellar tendon at joint line, introduce blunt trocar then 30° arthroscope. Anteromedial working portal: create under direct vision medially adjacent to patellar tendon at joint line (high AM portal 1cm more proximal reduces saphenous nerve injury area), ensure portal reaches lateral compartment for femoral drilling. Systematic examination following logical sequence: suprapatellar pouch (loose bodies, synovitis), patellofemoral joint (tracking, cartilage), medial gutter, medial meniscus (posterior horn first, then body, then anterior horn using probing), intercondylar notch and ACL remnant, lateral gutter, lateral meniscus, PCL integrity, cartilage surfaces of both femoral condyles and tibial plateau.

Exam Pearl

Technical Tip: EXAM KEY: 'I perform systematic diagnostic arthroscopy examining all structures in a logical sequence. I examine both menisci completely using probing - 40-50% have associated meniscal tears which must be identified and treated. I preserve any viable ACL remnant tissue as it contains proprioceptive mechanoreceptors and may aid revascularization. I identify and treat any meniscal or chondral pathology before proceeding with ACL reconstruction - concurrent meniscal repair improves outcomes but requires modified rehabilitation protocol.'

Dangers at this step

Missed meniscal tear - always complete systematic examination with probing especially posterior horn medial meniscus, missed tears lead to continued symptoms and poorer outcomes
Iatrogenic chondral damage - careful portal creation avoiding articular surface, damage from instruments especially in tight joint spaces
Infrapatellar nerve injury - unavoidable with anteromedial portal placement, occurs in 50-70% causing anterior knee numbness, counsel patient pre-operatively
Synovial fistula - ensure proper portal closure at end of case to prevent persistent drainage requiring secondary closure

Step 5: Notch Preparation

Notch Preparation: Remove ACL stump using arthroscopic shaver and basket forceps, preserving any posterior fibers at PCL to avoid PCL injury. Clear soft tissue from lateral wall and roof of notch to visualize bony landmarks clearly. Identify key anatomic structures: lateral intercondylar ridge (resident's ridge) marking anterior border of femoral footprint, over-the-top position posteriorly marking posterior boundary, bifurcate ridge (between AM and PL bundles) if visible. Notchplasty is NOT routine in modern ACL surgery - only perform if documented true bony impingement on extension test (2-3mm removal from lateral wall using burr), avoid aggressive notchplasty which removes footprint bone and creates too large tunnel. The goal is visualization not routine bone removal.

Exam Pearl

Technical Tip: EXAM KEY: 'I clear the notch to visualize landmarks while preserving the PCL posteriorly. I identify anatomic landmarks: resident's ridge which is the anterior margin of the femoral footprint, and bifurcate ridge separating AM and PL bundles. Routine notchplasty is controversial and NOT standard practice - I only perform it if true bony impingement exists on extension testing. Excessive notchplasty removes healthy footprint bone, may create oversized tunnel, and has not been proven to improve outcomes in anatomic reconstruction.'

Dangers at this step

PCL injury - stay anterior to posterior fibers, PCL injury causes posterior instability requiring complex reconstruction
Excessive notchplasty - removes footprint bone making anatomic tunnel placement difficult, creates oversized tunnel reducing fixation, no proven benefit in anatomic reconstruction
Inadequate visualization - must see lateral wall bony landmarks clearly for accurate anatomic tunnel placement, poor visualization leads to malposition
Cartilage damage from instruments - use careful technique especially with burr and shavers near articular surfaces of medial and lateral femoral condyles

Step 6: Femoral Tunnel Placement

Femoral Tunnel Placement: ANATOMIC SINGLE-BUNDLE TECHNIQUE: Flex knee 110-120° and drop foot of bed to position lateral wall of notch anteriorly for optimal access. Drill through anteromedial portal (transtibial technique is outdated and cannot achieve anatomic position). Center of femoral ACL footprint: 1-2mm anterior to over-the-top position, at 10:30 clock position (right knee) or 1:30 (left knee) on lateral wall when viewed at 90° flexion. Use resident's ridge as anterior landmark and over-the-top as posterior boundary. Place guidewire first, confirm position arthroscopically. Drill with offset guide and flexible reamers sequentially up to 0.5-1mm larger than graft diameter. Measure depth aiming for >30mm tunnel length. Ensure minimum 2mm posterior wall thickness - check by feeling posterior wall with probe (should be firm bone bridge not just soft tissue). Record tunnel position and length.

Exam Pearl

Technical Tip: EXAM KEY: 'I use anatomic single-bundle technique via trans-AM portal at 110-120° knee flexion. I aim for the center of the femoral footprint at 10:30 (right) or 1:30 (left) position using resident's ridge as my primary landmark. The key technical advance is drilling through AM portal which allows me to achieve this anatomic tunnel position - transtibial drilling forces a more anterior vertical tunnel at 11-12 o'clock which is non-anatomic and cannot achieve this position. This anatomic position improves rotational stability and reduces failure rates. I ensure adequate posterior wall minimum 2mm to prevent blowout by probing the wall.'

Dangers at this step

Posterior wall blowout - occurs if tunnel placed too posterior or reamed too shallow, causes fixation failure as suspensory device has no cortical bone to flip on, requires revision to more anterior position
Non-anatomic tunnel too anterior - creates vertical graft failing to control rotation, associated with higher failure rates and residual rotational laxity
Short tunnel length <25mm - inadequate fixation length especially for interference screw technique, aim for minimum 30mm
Medial femoral condyle cartilage damage - can occur with poor trans-AM portal drilling technique if drill angle diverges medially, careful alignment required

Step 7: Tibial Tunnel Placement

Tibial Tunnel Placement: Tibial footprint center anatomically located: posterior to anterior horn lateral meniscus attachment, just anterior to tibial spine, lateral to medial tibial spine. Place tibial drill guide at 55° angle (relative to tibial shaft in sagittal plane). Starting point on anterior tibia: at level of pes anserinus incision, 1-2cm medial to tibial tubercle on medial tibia. Drill guide pin under direct arthroscopic visualization watching entry point in joint to confirm proper position. Entry point in joint should be at center of tibial footprint - just anterior to tibial spine, lateral to medial spine, 7mm posterior to anterior edge of tibia. Ream over guidewire to graft diameter size (0.5-1mm larger than graft). Check final tunnel position: should be parallel to Blumensaat's line (roof of intercondylar notch) in full extension on lateral view - this is critical to avoid impingement.

Exam Pearl

Technical Tip: EXAM KEY: 'I place the tibial tunnel at 55° using a standard tibial guide. The critical check is tunnel position in full extension - the tunnel must be parallel to Blumensaat's line (roof of the notch). If the tunnel diverges from Blumensaat's line creating an angle, this indicates tunnel malposition which will cause roof impingement, loss of extension, and cyclops lesion formation. If not parallel, I must redrill the tunnel in correct position before proceeding. The entry point in the joint is centered on the tibial footprint just anterior to the tibial spine.'

Dangers at this step

Tunnel too anterior - most common error, causes graft impingement on roof of notch in extension, leads to loss of extension, cyclops lesion, anterior knee pain, and graft failure
Tunnel too posterior - creates vertical graft with poor rotational control, difficult to achieve adequate fixation, rare with proper technique
Tunnel too medial - risks injury to PCL and medial wall blowout into joint, inadequate bone bridge between tunnels
Posterior cortex blowout - if guide slips during reaming or excessive force used, creates large posterior defect requiring bone grafting before reconstruction

Step 8: Tunnel Assessment

Tunnel Assessment: Before graft passage, perform systematic tunnel position verification. With knee in full extension, arthroscope in lateral or anterolateral portal, assess: (1) Graft trajectory will sit parallel to Blumensaat's line (roof of notch) - any divergence indicates impingement risk; (2) No impingement of tunnel aperture on roof with knee in extension; (3) Adequate visualization of both femoral and tibial tunnel apertures arthroscopically; (4) Posterior wall of femoral tunnel intact - probe to check for minimum 2mm bone bridge; (5) Distance between tunnels adequate. If tunnel position suboptimal or impingement demonstrated, must redrill correctly positioned tunnel before graft passage. It is better to redrill than proceed with malpositioned tunnel.

Exam Pearl

Technical Tip: EXAM KEY: 'Before passing the graft, I meticulously verify tunnel positions with the knee in full extension. The graft must run parallel to Blumensaat's line - this is the critical check. Any angle of divergence between the planned graft trajectory and the roof means impingement risk and tunnel malposition requiring redrilling. I also check femoral posterior wall integrity by direct probing - must have solid 2mm bone bridge. If tunnels are malpositioned, I redrill correctly before graft passage. Proceeding with malpositioned tunnels guarantees poor outcome.'

Dangers at this step

Proceeding with malpositioned tunnels - leads to reconstruction failure, stiffness, impingement, early graft failure, better to redrill correctly than accept suboptimal position
Not checking knee in full extension - impingement only visible in extension, missing this leads to post-operative extension loss and cyclops lesion
Inadequate posterior wall check - relying on visualization alone, must probe wall to confirm adequate bone, thin wall will fail with suspensory device
Missing convergent tunnels - if tunnels too close together, creates bone bridge fracture risk and combined tunnel, check distance between apertures

Step 9: Graft Passage

Graft Passage: Pass #5 Ethibond suture (or dedicated passing suture) through tibial tunnel retrograde (from anterior tibia through joint), through joint under arthroscopic visualization, up into femoral tunnel and out far cortex using arthroscopic grasper. Secure passing suture to graft whipstitch on one end. Pull graft into tibial tunnel from anterior tibia, through joint, into femoral tunnel by applying steady traction to suture exiting femoral tunnel on anterolateral thigh. Watch entire passage arthroscopically. Check systematically: (1) Graft not twisted - whipstitches should be aligned indicating no twist, twisting reduces strength 30-50%; (2) Graft seated at aperture of femoral tunnel with no gap; (3) Graft fills tibial tunnel aperture completely; (4) No soft tissue interposition between graft and bone at either tunnel which would prevent healing.

Exam Pearl

Technical Tip: EXAM KEY: 'I pass a suture retrograde from tibia through joint and femoral tunnel, then pull the graft through by pulling on the suture. It is critical to ensure no graft twist during passage - twisting reduces tensile strength by 30-50% and is a primary technical error. I confirm the whipstitches are aligned indicating no twist. I confirm arthroscopically that the graft is fully seated at both tunnel apertures with no soft tissue interposition. Any soft tissue between graft and bone must be cleared as this prevents graft-to-bone healing.'

Dangers at this step

Graft twist - reduces tensile strength by 30-50%, primary preventable technical error, must confirm whipstitches aligned and graft not spiraled
Graft damage during passage - catching on tunnel edge or excessive force, inspect graft after passage for any fraying or damage
Soft tissue interposition - ACL stump remnant or synovium between graft and bone prevents incorporation, must clear under direct visualization
Graft not fully seated in femoral tunnel - leaves gap between graft and fixation device reducing effective fixation length, pull graft firmly into tunnel before fixation

Step 10: Femoral Fixation

Femoral Fixation: SUSPENSORY FIXATION PREFERRED FOR HAMSTRING GRAFT: Use adjustable cortical suspensory device (TightRope, ZipLoop, or adjustable Endobutton). Pass looped device through femoral tunnel exiting far cortex on anterolateral thigh. Flip button on far cortex - feel for click and see confirmation mark at skin exit. Apply tension to graft limb pulling graft into tunnel and seating button on cortex. Adjust loop length if using adjustable device to tension graft. Lock mechanism per manufacturer instructions. Tension should be firm but not overtight. ALTERNATIVE TECHNIQUE: bioabsorbable interference screw (PLLA or PDLA) size 7-9mm diameter x 25-30mm length inserted from AM portal, advanced alongside graft (not through graft), screw divergence angle must be minimal and parallel to graft. HYBRID TECHNIQUE (increasingly used): suspensory device plus interference screw for combined cortical strength and aperture fixation.

Exam Pearl

Technical Tip: EXAM KEY: 'For femoral fixation I prefer cortical suspensory device which provides excellent initial fixation strength exceeding 1000N and allows intraoperative tensioning adjustment. The device flips on the far cortex - I confirm this by feeling a distinct click and seeing the confirmation mark at the skin. Modern evidence supports suspensory devices over interference screw alone for hamstring grafts. Some surgeons add an interference screw (hybrid technique) for aperture fixation which reduces graft-tunnel motion, though this adds cost and the benefit is debated.'

Dangers at this step

Suspensory device not properly flipped - leads to fixation failure when loaded, must confirm flip by feel (click), visualization of mark, and resistance to pull
Interference screw divergence - if screw angle not parallel to graft direction, reduces fixation strength and may cut graft, ensure parallel trajectory
Graft laceration by screw - occurs if screw crosses through graft instead of alongside, or if screw oversized, inspect graft after screw insertion
Lateral cortex bone fracture - from excessive suspensory device tension or screw oversizing, rare with modern devices and proper technique

Step 11: Graft Tensioning & Cycling

Graft Tensioning & Cycling: Before tibial fixation perform critical tensioning protocol. Manually cycle graft through full ROM (0° extension to >120° flexion) 20-30 times applying moderate tension (20-30N manually) on tibial sutures. This cycling eliminates initial graft creep and preconditions the graft. After cycling, position knee at 20-30° flexion (NOT full extension which causes flexion contracture, NOT >30° which causes laxity). Apply anterior drawer force on proximal tibia translating it anteriorly to load the graft. Apply firm manual tension to graft by pulling tibial sutures (approximately 20-30N force, firm hand tension). Hold tension while assistant proceeds to tibial fixation. Do not release tension until fixation secured.

Exam Pearl

Technical Tip: EXAM KEY: 'I cycle the graft 20-30 times through full ROM to eliminate initial creep and precondition it to physiologic loading. I then tension and fix the graft at 20-30° flexion while applying anterior drawer force. This 20-30° position is critical and evidence-based - fixing in full extension risks flexion contracture which is difficult to treat, while fixing in >30° flexion results in a lax graft. The anterior drawer force during fixation ensures the graft is tensioned to restore normal tibial position.'

Dangers at this step

Inadequate tensioning during fixation - leads to lax reconstruction with residual anterior translation and instability requiring revision
Fixing in too much flexion >30° - results in lax graft when knee extends, causes residual instability and early failure
Fixing in full extension - risks flexion contracture which is a major complication causing anterior knee pain, difficult to treat
Not cycling graft before fixation - allows significant early laxity from creep in first few weeks, proper cycling reduces this substantially

Step 12: Tibial Fixation

Tibial Fixation: While maintaining graft tension at 20-30° flexion with anterior drawer force: Insert bioabsorbable interference screw (PLLA or PDLA, size 7-9mm diameter x 25-30mm length) alongside graft through tibial tunnel. Advance screw parallel to graft direction, ensuring screw does not cross through graft strands. Advance until screw flush with tibial bone surface or slightly countersunk (1-2mm below surface to prevent prominence). Alternative fixation: cortical button with post fixation using screw and spiked washer (backup technique), or screw-and-sheath device. After fixation complete, release tension slowly and test ROM and stability. Confirm adequate fixation by pulling on graft - should be solid with no movement.

Exam Pearl

Technical Tip: EXAM KEY: 'I use bioabsorbable interference screw at the tibia for aperture fixation. The screw must run parallel to the graft trajectory, not divergent - divergent screws have reduced fixation strength and may cut graft. I advance the screw until flush with bone or slightly countersunk to prevent painful prominence. Interference screws provide immediate rigid fixation strength of 400-600N and promote graft-to-bone healing at the aperture. Bioabsorbable screws avoid MRI artifact and do not need removal unlike metal screws.'

Dangers at this step

Screw divergence - reduces fixation strength significantly, may cut graft, ensure screw trajectory parallel to graft not divergent
Screw crosses through graft - graft laceration and immediate or delayed failure, ensure screw alongside graft in bone-graft interface
Excessive advancement - posterior tibial cortex fracture or penetration, stop when screw flush or slightly countersunk
Loss of tension during fixation - results in lax reconstruction, maintain tension throughout screw insertion until fully seated

Step 13: Final Assessment

Final Assessment: Perform systematic final checks before closure. (1) ROM testing - must achieve full passive extension to 0° (any extension deficit is unacceptable and must be addressed immediately), flexion >120°; (2) Impingement testing - with knee in full extension, arthroscopically visualize graft clearance from roof of notch, no contact or rubbing; (3) Stability testing - perform Lachman and pivot shift under arthroscopic visualization, graft should be visible and tensioned, endpoint should be firm; (4) Graft tension check - graft should be firm to palpation but not over-tight (over-constraining causes stiffness); (5) No hardware prominence - feel tibial screw should be flush; (6) Hemostasis achieved - clear visualization with minimal bleeding; (7) No loose bodies or instruments; (8) Recheck menisci for any missed pathology.

Exam Pearl

Technical Tip: EXAM KEY: 'I confirm full ROM especially full extension to 0° which is absolutely critical - loss of extension is a major complication causing anterior knee pain, patellofemoral problems, and poor outcomes. I perform Lachman and pivot shift to confirm stability - should have firm endpoint and negative pivot shift. The graft should be firm but not over-constrained. If any impingement exists with the knee in full extension, I must revise tunnel position - accepting impingement guarantees failure.'

Dangers at this step

Loss of extension - leads to anterior knee pain, patellofemoral problems, cyclops lesion, arthrofibrosis - must achieve 0° before leaving OR
Residual laxity - indicates technical error in tunnel position, tensioning, or fixation requiring immediate revision
Graft impingement in extension - causes stiffness, pain, and graft failure, must be corrected by tunnel revision if present
Missing concurrent pathology - always recheck menisci and articular surfaces, missed tears lead to persistent symptoms

Step 14: Irrigation & Closure

Irrigation & Closure: Copious irrigation with 3-4 liters normal saline to remove all debris and reduce inflammatory response. Inject local anaesthetic mixture (20ml 0.25% marcaine with 1:200,000 epinephrine, some add 4mg morphine) into joint and portal sites for post-operative analgesia. Remove instruments under arthroscopic visualization ensuring nothing left behind. Close portal sites with single 3-0 or 4-0 nylon interrupted suture each. Close hamstring harvest site in layers: repair sartorial fascia with 2-0 vicryl interrupted sutures, subcutaneous layer with 3-0 vicryl, skin with 3-0 monocryl subcuticular running suture or staples. Ensure hemostasis at harvest site. Apply sterile dressing to all wounds. Apply compression dressing from toes to upper thigh. Apply cryotherapy device (ice machine or cooling pad) if available to reduce swelling and pain.

Exam Pearl

Technical Tip: EXAM KEY: 'I irrigate thoroughly with 3-4L saline to reduce post-operative synovitis and hemarthrosis. I inject local anaesthetic into the joint and portals for multimodal analgesia. I close portals and harvest site meticulously - poor portal closure can lead to persistent synovial fistula requiring secondary closure. I apply cryotherapy and compression dressing to reduce swelling and pain. I do not routinely use drains in ACL reconstruction as they increase infection risk and do not improve outcomes.'

Dangers at this step

Inadequate irrigation - leaves debris and blood causing increased post-operative synovitis, pain, and stiffness
Synovial fistula from portal - occurs if portal not properly closed, causes persistent drainage requiring secondary closure with suture
Harvest site hematoma - ensure hemostasis before layered closure, large hematomas cause pain and may become infected
Compartment syndrome - rare but catastrophic complication, risk increased with tourniquet use, monitor overnight especially if tight dressing

Step 15: Post-Operative Orders

Post-Operative Orders: Immediate management: Ice/cryotherapy continuously for 24-48 hours, limb elevation above heart level, multimodal analgesia (paracetamol 1g QID, NSAIDs unless contraindicated, opioids PRN minimized). Mobilization: WBAT (weight bearing as tolerated) with crutches for comfort in locked hinged brace (or brace optional in selected patients). VTE prophylaxis: mechanical compression stockings (TED stockings), early mobilization and ankle pumps (chemical prophylaxis with LMWH or NOAC only if high-risk patient with previous VTE, thrombophilia, or other major risk factors). ROM exercises: Start immediately day 0-1 - quadriceps sets hourly, ankle pumps, heel slides for flexion, prone hangs or towel prop for extension. Brace locked in extension for ambulation initially, unlock for controlled ROM exercises. Physiotherapy referral day 1 for supervised exercise program. DVT education and warning signs. Wound care instructions. Follow-up appointment 2 weeks for wound check and rehabilitation review.

Exam Pearl

Technical Tip: EXAM KEY: 'Post-operatively I allow immediate WBAT with crutches - early weightbearing does not harm the graft and improves outcomes. Early ROM is critical - I start exercises day 1 with goal of full extension (0°) by 2 weeks and 90° flexion by 2 weeks. The brace is for comfort and protection against falls initially, not mandatory in all patients. I use multimodal analgesia minimizing opioids. VTE prophylaxis is primarily mechanical compression and early mobilization - chemical prophylaxis not routine unless patient has specific high-risk factors given low VTE rate (0.1-1%).'

Dangers at this step

Restricted ROM protocols - outdated practice, modern accelerated protocols with immediate ROM have better outcomes with lower stiffness rates
Delaying full extension goal - allowing extension deficit to persist beyond 2 weeks leads to chronic extension loss requiring manipulation or arthroscopic adhesiolysis
Over-reliance on opioids - use multimodal approach with paracetamol, NSAIDs, local anaesthetic, cryotherapy, minimize opioid use to reduce side effects and dependence
Not screening for VTE risk factors - rare but serious complication (0.1-1%), higher with tourniquet use, prolonged surgery, obesity, previous VTE, need to identify high-risk patients

Post-operative Care & Rehabilitation

Phase 1 (0-2 weeks): Goals - control swelling, full extension (0°), flexion to 90°, quad activation. WBAT with crutches, unlock brace for exercises. Exercises: quad sets hourly, SLR 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°), normal 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 >90% LSI, hop testing >90% LSI, full ROM, no effusion/pain, psychological readiness (ACL-RSI >56), sport-specific training complete. Progressive RTS: non-contact training, limited contact, full practice, competition. Optimal RTS 12 months for elite athletes.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"A 22-year-old male footballer presents with ACL rupture. Walk me through your management and discuss the key complications of ACL reconstruction and how you prevent them."

EXCEPTIONAL ANSWER

The most important complication requiring prevention is loss of extension occurring in 5-10% of cases, which causes anterior knee pain, patellofemoral problems, and poor functional outcomes. I prevent extension loss through multiple strategies: ensuring anatomic tunnel placement parallel to Blumensaat's line in extension to avoid impingement, not over-constraining the graft by fixing at appropriate tension at 20-30° flexion, and aggressive early ROM with goal of achieving full extension by 2 weeks post-operatively. Graft failure occurs in 5-15% overall but higher in young active males - I minimize this by using anatomic trans-AM portal technique for optimal tunnel positioning, ensuring graft diameter ≥8mm (I would not accept <8mm in this demographic), proper tensioning and cycling protocol, and most importantly criteria-based return to sport with minimum 9 months plus objective testing showing >90% LSI on strength and hop testing. Saphenous nerve injury causing medial leg numbness occurs in 5-10% from hamstring harvest - I prevent this by centering my incision over the pes anserinus, staying superficial to the sartorius fascia, and avoiding excessive medial dissection. Arthrofibrosis occurs in 2-5% - I prevent this by avoiding surgery during the acute inflammatory phase, ensuring no impingement, and using accelerated rehabilitation protocols. Infection risk is 0.3-1% which I minimize through perioperative antibiotics and meticulous sterile technique.

VIVA SCENARIOStandard

EXAMINER

"Why do you use hamstring autograft and what are the alternatives? Compare the graft choices and justify your selection for different patient populations."

EXCEPTIONAL ANSWER

I use 4-strand hamstring autograft because it provides excellent graft strength (initial strength 4090N, twice native ACL), has significantly lower anterior knee pain rates compared to BPTB (10% versus 30%), better cosmesis with smaller incisions, and avoids patella-related complications like fracture and kneeling pain. The main disadvantage is potential inadequate diameter <8mm in smaller patients, particularly females and adolescents, which has 2-3x higher failure rate. BPTB is the traditional gold standard with advantages of bone-to-bone healing which is faster than soft tissue (6-8 weeks vs 12+ weeks), consistent adequate size, and lower revision rates in some registry studies (3.7% vs 5.8% at 10 years in Danish Registry). However, BPTB has higher anterior knee pain (20-30%), more kneeling difficulty which persists long-term, and risk of patella fracture (0.5-1%). Quadriceps tendon is emerging as an excellent alternative with advantages of large diameter (8-10mm reliably), single tendon harvest, potentially lower donor site morbidity, and excellent strength properties. The disadvantages are technically more demanding harvest, larger anterior incision, and less long-term outcome data compared to hamstring and BPTB. For graft selection, I would choose hamstring in most primary ACL reconstructions if adequate diameter achievable (>8mm), choose BPTB in young high-risk males involved in cutting sports where revision rate data slightly favors BPTB or if hamstring diameter inadequate, and increasingly consider quadriceps tendon in larger patients, revision surgery, or when hamstring inadequate and want to avoid BPTB complications.

VIVA SCENARIOStandard

EXAMINER

"Explain your femoral tunnel positioning technique and why you use trans-anteromedial portal approach. What are the consequences of non-anatomic tunnel placement?"

EXCEPTIONAL ANSWER

I use trans-anteromedial portal drilling at 110-120° knee flexion to achieve anatomic femoral tunnel position. The center of the femoral ACL footprint is located 1-2mm anterior to the over-the-top position on the lateral wall of the intercondylar notch, which corresponds to the 10:30 clock position on a right knee or 1:30 on a left knee when viewed arthroscopically at 90° flexion. I use the lateral intercondylar ridge, called resident's ridge, as my primary anterior landmark, and the over-the-top position as the posterior boundary. The trans-AM portal technique is now considered gold standard because the transtibial drilling technique, which was standard until approximately 2005, cannot achieve anatomic tunnel position - it forces placement of a more anterior and vertical tunnel at 11-12 o'clock position which is non-anatomic. This anatomic positioning is critical because the native ACL controls both anterior translation and rotational stability, particularly internal rotation and the pivot shift phenomenon. Non-anatomic placement, particularly too anterior and vertical, results in a graft that adequately controls anterior translation on Lachman testing but fails to control rotational stability, resulting in persistent pivot shift, functional instability, and higher failure rates. Studies comparing transtibial to trans-AM portal techniques show improved rotational stability and lower failure rates with anatomic positioning. The other consequence of malposition is impingement - if the tibial tunnel is too anterior, the graft impinges on the roof of the notch in extension causing loss of extension, cyclops lesion formation, anterior knee pain, and eventual graft failure.