import { ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MedicalImage, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, VivaScenario, VivaScenarioSection } from '@/components/mdx' **Anatomic placement** in center of native footprint. Posterior to **resident's ridge** (anterior border of footprint). **Transportal** or **outside-in** technique. Avoid posterior blowout. Center in native footprint. **Posterior to anterior horn of lateral meniscus**. **Behind intersection of ACL stump and lateral meniscus**. Too anterior = roof impingement in extension. **Bone-to-bone healing** in tunnels. **Faster integration**. Higher **anterior knee pain** and kneeling pain. Some evidence of lower re-rupture in young athletes. **Soft tissue to bone healing** (slower). **Less anterior knee pain**. Need **minimum 8mm diameter** for strength. May have **hamstring weakness**. Quadrupled graft common. **ACL reconstruction** aims to restore knee stability through **anatomic tunnel placement** replicating native footprints, with **tunnel position being the most critical technical factor**. The **femoral tunnel** is placed posterior to the **resident's ridge** (anterior border of footprint) at approximately 10 o'clock (right knee) or 2 o'clock (left knee). The **tibial tunnel** center is positioned **posterior to the anterior horn of the lateral meniscus**—too anterior placement causes roof impingement in extension. **Graft options** include BTB (bone-to-bone healing, faster integration, more anterior knee pain), hamstring (less donor site morbidity, need ≥8mm diameter), quadriceps (increasing popularity), and allograft (revision/older patients). Grafts are tensioned at **15-20 degrees flexion**. Return to sport rates are **85-90%** with appropriate rehabilitation. **ACL reconstruction** aims to restore knee stability and allow return to pre-injury activity level. Modern technique emphasizes anatomic reconstruction replicating the native ACL footprints. ### Anatomic Reconstruction Anatomic single-bundle reconstruction places the graft in the center of the native ACL footprints. This contrasts with historical non-anatomic (isometric) techniques that placed the femoral tunnel more anterior and proximal. ### Single vs Double Bundle Most surgeons perform single-bundle reconstruction. Double-bundle (AM and PL bundles) aims to more closely replicate anatomy but has not shown clear superiority in outcomes. **Bone-Patellar Tendon-Bone (BTB)**: **Advantages**: - Bone-to-bone healing in tunnels (faster, stronger integration) - Some evidence of lower re-rupture in young athletes - Historical "gold standard" **Disadvantages**: - Anterior knee pain (up to 20%) - Kneeling pain - Risk of patellar fracture, tendon rupture - Fixed graft size **Use**: First-time ACL reconstruction in young athletes, particularly if early return to high-level sport is priority. **Hamstring Autograft (Semitendinosus +/- Gracilis)**: **Advantages**: - Less anterior knee pain - Smaller incision - Variable graft diameter (can quadruple) **Disadvantages**: - Soft tissue to bone healing (slower) - Graft may be small (less than 8mm increases failure) - Some hamstring weakness - Tunnel widening **Use**: First-time reconstruction, athletes without high anterior knee pain risk, patients concerned about kneeling. **Quadriceps Tendon**: - Full or partial thickness - Growing popularity - Bone block option - Good size **Allograft**: - Useful in revision - Older, lower-demand patients - Higher failure in young athletes - No donor site morbidity Allograft is best reserved for revision surgery or low-demand patients. ### Native ACL Anatomy The **anterior cruciate ligament** originates from the posteromedial aspect of the **lateral femoral condyle** and inserts on the **anterior tibial plateau**, between the tibial spines. **Two Functional Bundles**: 1. **Anteromedial (AM) Bundle**: - More anterior and proximal femoral attachment - Taut in **flexion** - Primary restraint to anterior tibial translation - Guides surgical technique in single-bundle reconstruction 2. **Posterolateral (PL) Bundle**: - More posterior and distal femoral attachment - Taut in **extension** - Controls rotational stability - Contributes to pivot shift phenomenon **Functional Significance**: AM bundle controls anteroposterior stability; PL bundle controls rotational stability. Single-bundle reconstruction aims to replicate combined function. **Femoral Attachment**: - Located on posteromedial aspect of lateral femoral condyle - Semicircular shape, approximately 18mm long - **Resident's ridge**: Bony landmark marking anterior border - **Lateral intercondylar ridge**: Proximal border - Direct (ligamentous) and indirect (fibrocartilage) insertions **Surgical Relevance**: - Single-bundle reconstruction targets center of footprint - Double-bundle targets centers of AM and PL bundles separately - Posterior to resident's ridge is critical landmark **Tibial Attachment**: - Broad, oval-shaped depression on anterior tibial plateau - Located between tibial spines - Area approximately 120-150 mm² - **Posterior to anterior horn of lateral meniscus** - **Lateral to medial tibial spine** **Surgical Landmarks**: - Behind intersection of ACL stump and lateral meniscus - Center of footprint is surgical target - Anterior placement causes roof impingement ### Blood Supply and Innervation **Blood Supply**: Middle genicular artery (branch of popliteal artery) provides majority of blood supply via synovial membrane. Poor intrinsic healing capacity explains need for reconstruction rather than repair. **Innervation**: Posterior articular nerve (branch of tibial nerve). Contains mechanoreceptors (Ruffini endings, Pacinian corpuscles) important for proprioception. ### ACL Injury Classification **ACL Injury Grades**: | Grade | Description | Clinical Features | Management | |-------|-------------|-------------------|------------| | **I (Sprain)** | Mild stretch, intact fibers | Pain, minimal laxity, negative Lachman | Non-operative | | **II (Partial)** | Partial tear, some fibers intact | Moderate laxity, soft endpoint | Variable - trial non-op vs reconstruction | | **III (Complete)** | Complete rupture | Positive Lachman, pivot shift | Reconstruction in active patients | **Clinical Testing**: - **Lachman test**: Most sensitive (95%) - Grade 1 (3-5mm), Grade 2 (5-10mm), Grade 3 (greater than 10mm) - **Anterior drawer**: Less sensitive than Lachman - **Pivot shift**: Most specific for rotational instability **Classification by Technique**: 1. **By Graft Type**: - Autograft: BTB, hamstring, quadriceps - Allograft: Tibialis, Achilles, hamstring 2. **By Bundle Number**: - Single-bundle (most common) - Double-bundle (AM + PL) 3. **By Femoral Drilling**: - Transtibial (historical) - Transportal (current standard) - Outside-in (independent positioning) 4. **By Approach**: - Primary reconstruction - Revision reconstruction - Augmentation with lateral tenodesis **ACL Injury Patterns**: | Pattern | Components | Frequency | |---------|------------|-----------| | **Isolated ACL** | ACL only | 30% | | **ACL + Meniscal** | ACL + medial/lateral meniscus | 40-60% | | **ACL + MCL** | ACL + medial collateral ligament | 20% | | **Unhappy Triad** | ACL + MCL + medial meniscus | 10% | | **Multiligament** | ACL + PCL +/- collaterals | 5% | **Bone Bruising Pattern**: Kissing contusions of lateral femoral condyle and posterolateral tibial plateau - pathognomonic of ACL injury on MRI. ### History **Essential History Elements**: - **Mechanism**: Non-contact pivoting injury most common; contact injury may suggest multiligament injury - **Pop felt**: 70% of patients describe audible/palpable pop - **Immediate swelling**: Haemarthrosis develops within 4-6 hours (contrast with meniscal injury - delayed effusion) - **Inability to continue activity**: Most cannot return to sport immediately - **Previous injuries**: Prior ACL injury to same or contralateral knee - **Giving way episodes**: Symptomatic instability since injury **Activity and Expectations**: - Sport type and level (pivoting vs linear sports) - Occupational demands - Expectation of return to sport - Age and skeletal maturity ### Examination **Key Clinical Tests**: | Test | Technique | Positive Finding | Sensitivity | |------|-----------|------------------|-------------| | **Lachman** | 20-30° flexion, anterior tibial translation | Soft endpoint, increased translation | 85-95% | | **Anterior Drawer** | 90° flexion, anterior tibial translation | Increased translation | 40-50% | | **Pivot Shift** | Valgus + internal rotation, flexion-extension | Clunk as tibia reduces | 35-95% | | **Lever Sign** | Supine, fist under proximal tibia | Heel doesn't lift off bed | 80-90% | **Additional Assessment**: - **ROM**: Document any extension deficit - **Effusion**: Large effusion suggests acute injury - **Collateral stability**: MCL/LCL testing - **Meniscal signs**: Joint line tenderness, McMurray's - **Neurovascular**: Particularly if multiligament injury suspected ### Imaging Assessment **Standard Radiographs** (AP, lateral, skyline): **Acute Findings**: - Usually normal - **Segond fracture**: Avulsion of lateral tibial plateau rim - pathognomonic of ACL injury - **Tibial spine avulsion**: Especially in adolescents - Lateral capsular sign **Pre-operative Assessment**: - Joint space narrowing (osteoarthritis) - Tunnel position from prior surgery (revision cases) - **Notch width**: Narrow notch may increase impingement risk - Limb alignment (varus/valgus) **Post-operative**: - Tunnel position assessment - Hardware position - Tunnel widening (follow-up) **Gold Standard for ACL Injury Diagnosis**: **Primary Signs of ACL Rupture**: - Non-visualization of ACL fibers - Discontinuity of fibers - Abnormal signal intensity - Horizontal fiber orientation (normally oblique) **Secondary Signs**: - **Bone bruise pattern**: Lateral femoral condyle + posterolateral tibial plateau (pathognomonic) - Anterior tibial translation - Uncovering of posterior horn lateral meniscus - Deep lateral femoral notch sign (greater than 1.5mm) - PCL buckling **Associated Pathology Assessment**: - Meniscal tears (40-60% of ACL injuries) - Collateral ligament injury - Chondral damage - Posterolateral corner injury **CT Scan**: - Useful for revision surgery - assess tunnel position and size - 3D reconstruction for complex cases - Tibial spine fracture assessment **Stress Radiographs**: - KT-1000/KT-2000 arthrometer: Objective measurement of anterior translation - Side-to-side difference greater than 3mm is significant - Used in research and some clinical settings **Diagnostic Arthroscopy**: - Rarely indicated purely for diagnosis (MRI usually sufficient) - Performed at time of reconstruction - Allows assessment and treatment of associated pathology ### Treatment Algorithm **Indications for Non-operative Management**: - Low-demand patients - Older, sedentary individuals - No symptomatic instability - Willing to modify activities - Partial tears with minimal laxity **Non-operative Protocol**: 1. **Acute Phase** (0-2 weeks): - RICE protocol - Protected weight-bearing - Gentle ROM exercises - Quadriceps activation 2. **Rehabilitation Phase** (2-12 weeks): - Progressive strengthening - Proprioceptive training - Stationary cycling - Aquatic therapy 3. **Return to Activity**: - Functional brace for sport - Avoid pivoting/cutting sports - Activity modification **Failure of Non-operative Treatment**: Symptomatic instability (recurrent giving way) despite rehabilitation indicates need for reconstruction. **Absolute Indications for Reconstruction**: - Symptomatic instability affecting ADLs - Combined ligament injuries requiring surgery - Repairable meniscal tear in unstable knee (ACL reconstruction improves meniscal healing) **Strong Relative Indications**: - Young, active patient (less than 25 years) - High-level athlete wanting return to pivoting sports - High-demand occupation - High-grade pivot shift - Meniscal injury at high risk of further damage **Relative Contraindications**: - Significant osteoarthritis - Limited ROM (not yet restored) - Active infection - Unrealistic patient expectations **Timing**: Optimal timing is 4-8 weeks post-injury with full ROM restored and minimal effusion. **Procedures Commonly Combined with ACL Reconstruction**: 1. **Meniscal Surgery** (40-60% of cases): - Meniscal repair preferred over meniscectomy - ACL reconstruction improves meniscal healing rates - Address at time of ACL reconstruction 2. **Collateral Ligament Management**: - Isolated MCL: Non-operative treatment, stage ACL reconstruction - LCL/posterolateral corner: May require reconstruction 3. **Lateral Extra-articular Tenodesis (LET)**: - STABILITY study: 87% reduction in graft rupture - Consider in high-risk patients: young, high-grade pivot shift, returning to pivoting sport - Modified Lemaire or iliotibial band tenodesis 4. **Chondral Procedures**: - Debridement of unstable fragments - Microfracture or osteochondral grafting if indicated **Goal**: Anatomic position in center of native femoral footprint. **Landmarks**: - **Resident's ridge**: Bony ridge marking anterior edge of footprint - Posterior to resident's ridge - Center of combined AM/PL footprint (single bundle) **Technique Options**: - **Transportal**: Drill through AM portal with knee hyperflexed. Better anatomic position. - **Transtibial**: Drill through tibial tunnel. Historical technique, may limit anatomic positioning. - **Outside-in**: Drill from lateral femoral cortex. Allows independent positioning. **Clock Position**: 10 o'clock (right knee) or 2 o'clock (left knee) for single bundle. Avoid too vertical. **Goal**: Anatomic position in center of native tibial footprint. **Landmarks**: - Posterior to anterior horn of lateral meniscus - Lateral to medial tibial spine - Behind intersection of ACL stump remnant and lateral meniscus **Errors**: - **Too anterior**: Roof impingement in extension. Most common error. Causes graft failure. - **Too posterior**: Less common but affects stability. **Technique**: Use tibial guide (usually 55-65 degrees). Start point on anteromedial tibia. Confirm position arthroscopically. **Graft Preparation**: Size to match tunnels. BTB: Bone plugs sized. Hamstring: Whipstitch ends, size diameter. **Passage**: Pass graft through tibial tunnel, into joint, then into femoral tunnel. **Fixation**: - **Femoral**: Suspensory (EndoButton, TightRope), interference screw, cross-pin - **Tibial**: Interference screw, post fixation, staple - **Tensioning**: At 15-20 degrees flexion. Apply tension while cycling knee. Proper tensioning and fixation are critical for graft function and longevity. ### ACL Reconstruction Complications **Intraoperative Complications**: | Complication | Cause | Prevention/Management | |--------------|-------|----------------------| | **Posterior blowout** | Femoral tunnel too posterior | Careful guide placement, visualize posterior cortex | | **Graft damage** | Improper handling, excessive tension | Avoid clamping, gentle passage | | **Neurovascular injury** | Lateral femoral drill exit | Protect soft tissues, limit drill depth | | **Tunnel malalignment** | Poor visualization, incorrect technique | Fluoroscopy, anatomic landmarks | **Early Post-operative** (0-6 weeks): - **Haemarthrosis**: Common, manage with aspiration if tense - **Infection**: 0.5-1% incidence, aggressive treatment required - **DVT/PE**: Thromboprophylaxis, early mobilization - **Nerve injury**: Saphenous nerve (hamstring harvest), peroneal nerve (positioning) **Late Complications**: | Complication | Incidence | Risk Factors | Management | |--------------|-----------|--------------|------------| | **Graft failure/re-rupture** | 5-15% | Young age, return to pivoting sport, small graft | Revision ACL reconstruction | | **Arthrofibrosis** | 5-10% | Early surgery, aggressive early rehab | Manipulation, arthroscopic lysis | | **Extension deficit** | 5-10% | Anterior tibial tunnel, cyclops lesion | Arthroscopic debridement | | **Tunnel widening** | 20-30% | Soft tissue grafts, fixation issues | Usually asymptomatic | | **Osteoarthritis** | Long-term | Meniscal injury, cartilage damage | Symptomatic treatment | **Cyclops Lesion**: - Fibrous nodule anterior to graft - Causes mechanical block to extension - Arthroscopic excision with good outcomes **BTB Graft Complications**: - Anterior knee pain: 10-20% - Kneeling pain: 15-30% - Patellar fracture: less than 1% - Patellar tendon rupture: Rare - Patellofemoral crepitus **Hamstring Graft Complications**: - Hamstring weakness: Variable - Tunnel widening: More common than BTB - Saphenous nerve injury: During harvest - Graft too small: less than 8mm associated with failure **Allograft Complications**: - Higher failure rate in young athletes - Disease transmission (rare with modern processing) - Slower incorporation - **Tunnel position**: Anatomic placement prevents impingement and improves outcomes - **Graft diameter**: Minimum 8mm to reduce failure risk - **Timing**: Avoid early surgery to prevent arthrofibrosis - **Rehabilitation**: Protocol-based progression prevents re-rupture ### Rehabilitation Protocol **Phase 1: Protection Phase** (0-2 weeks) **Goals**: - Protect graft - Control pain and swelling - Restore full extension - Achieve 90° flexion **Weight-Bearing**: - Partial weight-bearing with crutches - Weight-bearing as tolerated by 2 weeks (graft dependent) **Exercises**: - Quadriceps setting (isometrics) - Straight leg raises (when quad control achieved) - Ankle pumps, heel slides - Passive extension to 0° (critical) - Patellar mobilization **Modalities**: - Ice, elevation - Compression - Gentle ROM exercises **Phase 2: Early Rehabilitation** (2-6 weeks) **Goals**: - Full ROM (0-130°) - Normal gait pattern - Progressive strengthening **Weight-Bearing**: - Full weight-bearing without crutches by 4-6 weeks - Normal gait pattern **Exercises**: - Closed kinetic chain exercises (mini squats, leg press) - Stationary cycling - Pool exercises - Progressive ROM exercises - Core strengthening **Restrictions**: - No open chain extension exercises (0-45°) - No running or jumping - Brace optional (surgeon preference) **Phase 3: Strengthening Phase** (6-12 weeks) **Goals**: - Strength 70% of contralateral - Single leg balance - Begin sport-specific training **Activities**: - Increased resistance training - Balance and proprioception - Light jogging (after 12 weeks) - Sport-specific drills (non-contact) **Phase 4: Return to Sport** (4-9 months) **Criteria for Sport Return**: - Isokinetic strength greater than 85% of contralateral - Single-leg hop test greater than 85% - No pain or effusion - Psychological readiness - Passed functional testing battery **Timeline**: - Non-contact training: 4-6 months - Full contact practice: 6-9 months - Competition: 9-12 months (depends on sport level) Modern protocols emphasize **criteria-based** rather than time-based return. Key metrics include: - Quadriceps strength index greater than 90% - Hop testing battery greater than 90% - ACL-RSI psychological score greater than 70 - Completed sport-specific training without symptoms ### ACL Reconstruction Outcomes **Overall Success Rates**: | Outcome Measure | Rate | Notes | |-----------------|------|-------| | **Knee stability** | 85-95% | Negative pivot shift | | **Return to sport** | 65-85% | Same level as pre-injury | | **Patient satisfaction** | 85-95% | IKDC, Lysholm scores | | **Graft survival** | 85-90% at 10 years | Varies by graft type | **Functional Outcome Scores**: - **IKDC subjective score**: Improvement from 50 to 85+ - **Lysholm score**: Improvement to 85-90+ - **Tegner activity scale**: Often 1-2 levels below pre-injury **Long-term Considerations**: - 50-70% develop radiographic OA by 15-20 years - Symptomatic OA less common - Meniscal injury at time of ACL injury is major risk factor for OA **Graft-Specific Outcomes**: | Outcome | BTB | Hamstring | Significance | |---------|-----|-----------|--------------| | **Re-rupture rate** | 5-8% | 8-12% | BTB slightly lower | | **Anterior knee pain** | 15-20% | 5-10% | HS lower | | **Kneeling pain** | 20-30% | 5-10% | HS lower | | **Extension loss** | 5% | 5% | Similar | | **Stability** | Excellent | Excellent | Similar | **Evidence Summary**: - Meta-analyses show similar overall outcomes - BTB may have slight advantage in stability - Hamstring has lower donor site morbidity - Graft diameter more important than graft type **Risk Factors for Poor Outcome**: **Patient Factors**: - Young age (less than 20 years): Higher re-rupture risk - Female sex: Higher re-rupture in some studies - High-level pivoting sport return - Delayed rehabilitation **Surgical Factors**: - Graft diameter less than 8mm - Non-anatomic tunnel placement - Inadequate fixation - Unaddressed associated injuries **Revision ACL Reconstruction**: - Success rate 75-85% (lower than primary) - Higher failure rate in revision of revision - Often requires staged procedures - Consider lateral tenodesis augmentation **A:** Placing the tunnel **too anterior**. This causes roof impingement in extension, leading to graft failure, loss of extension, and anterior knee pain. **A:** **8mm**. MOON cohort data demonstrates that grafts less than 8mm in diameter have significantly higher failure rates. Always ensure adequate graft size. **A:** A bony ridge on the lateral femoral wall that marks the **anterior border** of the native ACL femoral footprint. The femoral tunnel should be placed **posterior** to this landmark. **A:** **10 o'clock** for right knee, **2 o'clock** for left knee. This represents the center of the native ACL footprint and avoids the vertical (12 o'clock) position of older non-anatomic techniques. **A:** **15-20 degrees** of flexion. The knee should be cycled several times to eliminate creep before final fixation. ### Australian ACL Practice **ACL Injury in Australia**: - **Incidence**: Approximately 17,000 ACL reconstructions performed annually - **Peak age group**: 15-25 years - **Sex distribution**: Males have higher absolute numbers; females have 2-3x higher rate in same sports - **High-risk sports**: AFL, netball, soccer, rugby, skiing **Australian Football League (AFL)**: - ACL injury rate: 0.8 per club per season - Major cause of games missed - Significant media and research attention **Netball**: - One of highest ACL injury rates in female sport - Knee Injury Prevention Program (KIPP) widely promoted **Public System Coverage**: ACL reconstruction and associated procedures are covered under the Australian public hospital system. Surgical procedures including primary and revision ACL reconstruction, combined ligament reconstructions, diagnostic arthroscopy, and meniscal surgery are fully funded. **Note**: Wait times vary by state. Private insurance covers procedures with potential gap fees. **Private Health Insurance**: - Most policies cover ACL reconstruction - Excess and gap payments apply - Pre-existing condition exclusions may apply for some patients **Australian Guidelines and Resources**: **AOSSM/ESSKA/ISAKOS Consensus**: - Anatomic reconstruction recommended - Graft choice based on patient factors - Minimum 8mm graft diameter **Australian Knee Society**: - Rehabilitation protocols - Return to sport criteria - Registry data contribution **State Sporting Organizations**: - ACL injury prevention programs - Injury surveillance systems - Return to play protocols **Research Contribution**: - MARS (Multicenter ACL Revision Study) - Australian centers contributing - STABILITY Study (lateral tenodesis) - significant Australian authorship - La Trobe Sport and Exercise Medicine Research Centre Australian surgeons follow international consensus on anatomic reconstruction with graft selection based on patient factors. FIFA 11+, Netball Australia KNEE Program, and AFL-specific programs actively promoted in Australian sport.

ACL Reconstruction Technique

ACL Reconstruction Technique