import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Posterior to posterior capsule, 9mm from lateral meniscus, 13mm from medial meniscus at the popliteal hiatus. Closest during femoral tunnel drilling (average 7mm). **Protection**: NEVER over-drill femoral tunnel posteriorly. Use retractor in back of intercondylar notch during drilling. Confirm 2mm posterior cortical rim on fluoroscopy. If pulsatile bleeding, immediate tourniquet and vascular surgery consult. Monitor distal pulses post-operatively. **Location**: Posterior to sartorius tendon at medial joint line, 4-6mm from posteromedial capsule. At risk during hamstring harvest, medial portal placement, and tibial tunnel drilling. **Protection**: Oblique hamstring incision 3cm below joint line, blunt dissection to sartorius. Stay anterior to gracilis tendon insertion. Identify and protect during tibial tunnel reaming. Posteromedial portal with direct visualization. **Location**: Wraps around fibular neck 1-2cm distal to joint line posterolaterally. Lateral portal and posterolateral corner reconstruction put it at risk. Only 10mm from posterolateral capsule. **Protection**: Avoid lateral portal more than 1cm below joint line. Knee flexion relaxes nerve. Palpate fibular neck during ALL procedures. If ALL reconstruction needed, identify nerve directly. Post-op foot drop = urgent EMG/exploration. **Location**: Posterior cortex of lateral femoral condyle - at risk during femoral tunnel drilling, especially if drilling too posterior or with excessive reaming in revision setting with soft bone. **Protection**: Fluoroscopy to confirm tunnel position before reaming. Aim for 2mm posterior cortical rim. Use smaller reamer if tunnel widened. Anteromedial portal drilling allows better visualization than transtibial. **Location**: Posterior tibial cortex at risk if tibial tunnel angle too horizontal or over-drilled in revision with tunnel widening. Neurovascular structures directly posterior. **Protection**: Tibial guide at 55-60° angle. Fluoroscopy confirmation before over-reaming. If tunnel widened, use smaller graft or bone plug technique. Staged approach if massive widening. **Patient Position**: Supine with leg holder, tourniquet high on thigh **Surgical Approach**: Arthroscopic with possible open tunnel revision or staged bone grafting **Essential Equipment**: CT scan for tunnel assessment, fluoroscopy, revision ACL instrumentation, bone grafting materials, backup graft options ### Causes of ACL Reconstruction Failure (MARS Study Classification) | Category | Cause | Frequency | Key Features | |----------|-------|-----------|--------------| | Technical | Femoral tunnel malposition | 25-30% | Too anterior, too vertical - leads to vertical graft, impingement | | Technical | Tibial tunnel malposition | 10-15% | Too anterior = extension impingement, too posterior = flexion loss | | Technical | Inadequate notchplasty | 5-10% | Graft impingement in notch roof | | Biological | Failed incorporation | 15-20% | Graft intact but incompetent at 6-12 months | | Traumatic | Re-injury | 20-25% | New trauma to healed graft, contact sport | | Unaddressed | Missed PLC injury | 10-15% | Chronic posterolateral instability, varus thrust | | Unaddressed | Untreated meniscal pathology | 5-10% | Meniscal deficiency leads to increased graft load | | Unaddressed | Uncorrected malalignment | 5-10% | Varus alignment with PLC deficiency | **Investigation Protocol:** - CT scan: Tunnel position, widening, confluence assessment - MRI: Graft integrity, meniscal status, cartilage damage - Stress radiographs: Compare to contralateral, assess ligamentous laxity - Clinical: Pivot shift grade, varus/valgus opening, dial test for PLC ### CT Tunnel Assessment Protocol | Parameter | Measurement | Clinical Significance | |-----------|-------------|----------------------| | Tunnel diameter | Less than 14mm acceptable, more than 16mm = bone graft | Larger tunnels = insufficient rim for fixation | | Position | Compare to anatomic footprint | Malposition = primary indication for revision | | Confluence risk | Distance between old and proposed new tunnel | Less than 2mm rim = confluence likely | | Hardware position | Screws in or protruding into tunnel | May need removal before drilling | | Bone quality | Sclerosis, osteolysis | Affects healing and fixation | **Tunnel Widening Causes:** - Mechanical: Graft-tunnel motion, bungee effect - Biological: Synovial fluid ingress, osteolysis from bioabsorbable screws - Combined: Most common scenario **Staging Decision Algorithm:** 1. Tunnels less than 12mm, well-positioned → Use existing tunnels 2. Tunnels malpositioned, less than 14mm, non-confluent → One-stage, new tunnels 3. Tunnels more than 14-16mm OR confluence likely → Two-stage with bone grafting 4. Active infection → Staged debridement and delayed reconstruction ### Graft Options for Revision ACL | Graft | Advantages | Disadvantages | Best Indication | |-------|------------|---------------|-----------------| | Contralateral BPTB | Gold standard autograft, bone-to-bone healing | Donor site morbidity, anterior knee pain | Young athlete, failed ipsilateral BPTB | | Ipsilateral Quad Tendon | Strong, thick graft, low morbidity | Learning curve, variable bone plug | Failed hamstring primary, intact quad | | Contralateral Hamstring | Familiar technique | Less stiff than BPTB, donor knee morbidity | Failed ipsilateral hamstring | | Allograft (BPTB/Achilles) | No donor morbidity, large size | Higher failure in young (MARS study), disease transmission | Older patient, low demand, multiligament | | Fresh-frozen Achilles | Very strong, large | Slower incorporation, immunogenicity | Massive tunnels, multiligament | **MARS Study Evidence (2014):** - Allograft 2x higher failure rate vs autograft in patients younger than 25 - No difference in patients older than 40 - Autograft preferred for high-demand young athletes **Graft Selection Algorithm:** 1. Young athlete, high demand → Contralateral BPTB or ipsilateral quad 2. Previous hamstring harvest → Quad tendon or contralateral BPTB 3. Previous BPTB harvest → Contralateral BPTB or quad tendon 4. Multiple prior surgeries → Allograft may be only option 5. Low demand, older patient → Allograft acceptable ### Anterolateral Ligament Reconstruction | Indication | Technique | Evidence | |------------|-----------|----------| | High-grade pivot shift (Grade 3) | Iliotibial band autograft or allograft | Reduces pivot shift, may reduce re-rupture | | Young athlete, high-risk sport | Lateral extra-articular tenodesis | STABILITY study: 2.5% vs 5.7% failure | | Revision with rotational instability | Combined ACL + ALL | Increasing evidence for benefit | | Prior failed revision | Standard in some centers | Expert consensus | ### High Tibial Osteotomy Indications | Scenario | Timing | Rationale | |----------|--------|-----------| | Chronic PLC deficiency with varus | Before or concurrent with ACL | Corrects thrust, protects graft | | Medial compartment OA with ACL deficiency | Staged or concurrent | Unloads medial, protects graft | | Varus alignment more than 3° | Consider concurrent | Reduces graft strain | | Triple varus knee | Essential component | Must address alignment first | ### Meniscal Considerations - **Repair if possible**: Meniscal preservation protects cartilage and graft - **Root repair**: Critical to prevent extrusion and OA - **MAT**: Consider if meniscal deficiency with symptoms - **Timing**: Concurrent with revision ACL if possible ### Revision ACL Outcomes (MARS Study) | Outcome | Rate | Notes | |---------|------|-------| | Re-revision rate at 2 years | 4% | Higher than primary (2%) | | Graft failure at 2 years | 24% | Combined re-tear and functional failure | | Return to pre-injury sport | 40-50% | Lower than primary (65-70%) | | IKDC grade A/B | 60-70% | Lower than primary (85%) | | Patient satisfaction | 75-80% | Lower than primary (90%) | **Risk Factors for Revision Failure:** - Age younger than 25 years - Allograft use - Previous revision (2nd revision worse than 1st) - Meniscal deficiency - Uncorrected alignment - High-risk sport return **Level I Evidence:** - MARS Group (2014): Autograft superior to allograft in young - STABILITY Trial (2022): ALL augmentation reduces re-rupture from 5.7% to 2.5% - MOON Group: Meniscal preservation improves outcomes **Key Takeaways:** - Counsel patients: outcomes inferior to primary surgery - Address all pathology simultaneously when possible - Consider ALL augmentation in high-risk revisions - Autograft preferred in young, active patients ### Step 1: PREOPERATIVE ASSESSMENT AND FAILURE ANALYSIS PREOPERATIVE ASSESSMENT: CT scan MANDATORY to assess tunnel position, widening, and confluence risk. MRI for graft integrity, meniscal/cartilage status. Clinical exam: pivot shift grade, varus/valgus testing, dial test for PLC. IDENTIFY CAUSE OF FAILURE: technical (tunnel malposition), biological (incorporation), traumatic (re-injury), or unaddressed pathology (missed PLC, meniscal deficiency, malalignment). **Technical Tip**: EXAM KEY: MARS Study showed 80% of failures had identifiable technical cause. Femoral tunnel too ANTERIOR is most common error. CT is ESSENTIAL - correlate 3D position with failure mechanism. Check for hardware that needs removal. - Missed cause of failure leads to repeat failure - Inadequate imaging leads to intraoperative surprises ### Step 2: STAGING DECISION STAGING DECISION: One-stage if tunnels less than 14mm and non-confluent with proposed new position. Two-stage if: (1) tunnel widening more than 14-16mm, (2) confluence likely (less than 2mm between old and new tunnel), (3) active/recent infection, (4) massive bone loss requiring grafting. Document decision and communicate with patient regarding implications. **Technical Tip**: EXAM KEY: Two-stage adds 3-6 months but allows bone incorporation for better fixation. One-stage is preferred when possible for patient convenience. Use 3D CT reconstruction to plan new tunnel position relative to old. - One-stage with inadequate bone = fixation failure - Confluence creates communication between tunnels = instability ### Step 3: GRAFT HARVEST GRAFT SELECTION HIERARCHY: (1) Contralateral BPTB - gold standard autograft, bone-to-bone healing. (2) Ipsilateral quad tendon - thick, strong, low morbidity if previous hamstring used. (3) Allograft - for older/lower demand patients (MARS: 2x failure in under 25). Prepare graft on back table: size appropriately, mark orientation. Have backup plan if primary graft unavailable. **Technical Tip**: EXAM KEY: MARS Study Level I evidence: autograft SUPERIOR to allograft in patients younger than 25. Quad tendon graft 9-10mm thick, comparable strength to BPTB. If contralateral knee, counsel about bilateral morbidity. - Saphenous nerve injury with hamstring harvest - Patellar fracture with BPTB harvest - Inadequate graft size ### Step 4: DIAGNOSTIC ARTHROSCOPY AND GRAFT REMOVAL DIAGNOSTIC ARTHROSCOPY: Standard portals, may need modified placement if scar tissue. Systematic evaluation: graft remnant (probe for competence), meniscal status, cartilage grade, PCL integrity. REMOVE FAILED GRAFT: use shaver, careful debridement of scar tissue. Preserve notch roof. Identify existing tunnel apertures and assess for sclerosis. **Technical Tip**: EXAM KEY: Probe the graft remnant - if it's intact but incompetent (soft, stretched), this is BIOLOGICAL failure. May retain some fibers if well-positioned to augment new graft. Document meniscal status - will you repair or transplant? - Popliteal injury if aggressive posterior debridement - Chondral damage from instruments - Incomplete graft removal causing impingement ### Step 5: HARDWARE REMOVAL HARDWARE REMOVAL: Remove interference screws if protruding into tunnel or if new tunnel position requires it. Bioabsorbable screws may be expanded/fragmented - curette out debris. Metal screws may require trephine or reverse threader. Document: bone quality after removal, any bone loss, tunnel dimensions after debridement. **Technical Tip**: EXAM KEY: Have multiple extraction tools available: trephines, reverse threaders, bone tamps. Femoral screw may require outside-in or mini-open lateral approach for access. Leave well-positioned screws if not interfering. - Femoral condyle fracture with aggressive extraction - Stripped screw head requiring trephine - Posterior wall blowout ### Step 6: TUNNEL PREPARATION TUNNEL MANAGEMENT OPTIONS: (1) Use existing tunnels if well-positioned and less than 12mm. (2) New tunnels if malpositioned but less than 14mm and non-confluent - drill new anatomic position. (3) Bone graft if more than 14-16mm or confluence - pack with autograft/allograft, stage 3-6 months. Confirm new position with fluoroscopy before reaming. **Technical Tip**: EXAM KEY: Anatomic femoral tunnel at 1:30-2:00 (right knee) or 10:00-10:30 (left knee), low on lateral wall. Tibial tunnel in posterior half of native ACL footprint. Use fluoroscopy to confirm 2mm posterior cortical rim before reaming femoral tunnel. - Posterior wall blowout with over-reaming - Tunnel confluence creating instability - Popliteal injury with deep femoral drilling ### Step 7: NEW TUNNEL CREATION NEW TUNNEL DRILLING: Femoral tunnel via anteromedial portal (preferred) or outside-in for difficult cases. Tibial tunnel with standard ACL guide at 55-60°. Use smaller reamers if bone quality poor or tunnels expanded. Confirm tunnel position and length with measurements and fluoroscopy. Avoid posterior wall blowout on femur, anterior plateau fracture on tibia. **Technical Tip**: EXAM KEY: Anteromedial portal drilling allows independent femoral tunnel in anatomic position. Knee at 110-120° flexion for AM portal drilling. If concerned about posterior wall, start smaller reamer or use outside-in technique with fluoroscopy guidance. - Posterior wall blowout - reduced to 2mm rim - Popliteal artery injury - only 7mm from femoral tunnel - Peroneal nerve with lateral drilling ### Step 8: GRAFT PASSAGE AND FIXATION GRAFT PASSAGE: Pass graft with appropriate tension, confirm orientation. FIXATION: Start with femoral side - interference screw, suspensory button, or hybrid. Cycle graft 20-30 times to remove creep. Fix tibial side at 20-30° flexion with appropriate tension. Avoid over-tensioning which limits ROM. **Technical Tip**: EXAM KEY: Suspensory fixation (EndoButton, TightRope) useful in revision with poor bone stock. Interference screw requires adequate bone rim. Hybrid fixation (interference + backup) for maximum security. Test tension: should allow 1-2mm laxity at full extension. - Over-tensioning = loss of extension (flexion contracture) - Under-tensioning = persistent laxity - Graft twist reducing strength ### Step 9: ADJUNCT PROCEDURES ADJUNCT PROCEDURES: Meniscal repair/transplant if deficient - PRESERVE MENISCUS. High tibial osteotomy if chronic PLC with varus thrust (can be staged or concurrent). Anterolateral ligament reconstruction if: high-grade pivot shift (Grade 3), young high-risk athlete, revision setting. Address all pathology to maximize success. **Technical Tip**: EXAM KEY: STABILITY Trial - ALL reconstruction reduces re-rupture from 5.7% to 2.5%. Consider in all high-risk revisions. Triple varus knee (bone varus + PLC + thrust) MUST have HTO before or with ACL. Meniscal MAT for symptomatic deficiency. - Missed PLC = ongoing instability despite ACL revision - Uncorrected varus = graft overload and failure - Nerve injury with ALL reconstruction ### Step 10: FINAL ASSESSMENT AND CLOSURE FINAL ASSESSMENT: Arthroscopic confirmation of graft position, tension, and absence of impingement. Full ROM check - should achieve full extension and at least 120° flexion. Lachman and pivot shift testing - should be negative. Document findings. Standard closure with portal sites. Brace in extension. **Technical Tip**: EXAM KEY: Full extension is CRITICAL - flexion contracture severely limits function. If impingement on notch, perform notchplasty. Photo-document graft position for records. Aggressive early extension exercises post-op. - Unrecognized impingement → graft failure - Inadequate hemostasis → hemarthrosis - Flexion contracture if not achieving extension ## References 1. Wright RW, et al. Revision ACL Reconstruction Outcomes: MARS Group Results at 2 Years. JBJS. 2014;96(8):e65. **LEVEL I** 2. Getgood AM, et al. Lateral Extra-articular Tenodesis Reduces Failure of Hamstring Tendon Autograft Anterior Cruciate Ligament Reconstruction: 2-Year Outcomes From the STABILITY Study. Am J Sports Med. 2020;48(2):285-297. **LEVEL I** 3. MOON Knee Group. Effect of Meniscal Tears on ACL Reconstruction Outcomes: A Systematic Review. Am J Sports Med. 2019;47(9):2246-2256. **LEVEL I** 4. Eberbach H, et al. Tunnel widening after anterior cruciate ligament reconstruction - systematic review with meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2022;30(2):677-691. **LEVEL I** 5. Sonnery-Cottet B, et al. Anterolateral Ligament Reconstruction Is Associated With Significantly Reduced ACL Graft Rupture Rates at a Minimum Follow-up of 2 Years: A Prospective Comparative Study of 502 Patients. Am J Sports Med. 2017;45(7):1547-1557. **LEVEL II** 6. Parkinson B, et al. Revision Anterior Cruciate Ligament Reconstruction in Professional Athletes. Am J Sports Med. 2018;46(9):2194-2204. **LEVEL III** 7. Houck DA, et al. Outcomes of Anterior Cruciate Ligament Reconstruction With Quadriceps Tendon Versus Patellar Tendon or Hamstring Tendon Autografts: A Systematic Review and Meta-analysis. Am J Sports Med. 2021;49(5):1423-1434. **LEVEL I** 8. Noyes FR, Barber-Westin SD. Revision Anterior Cruciate Ligament Reconstruction: Report of 11-Year Experience and Results in 114 Consecutive Patients. Instr Course Lect. 2001;50:451-461. **LEVEL IV** 9. Grassi A, et al. Two-stage revision anterior cruciate ligament reconstruction: a systematic review of the literature. Knee Surg Sports Traumatol Arthrosc. 2019;27(6):1829-1842. **LEVEL III** 10. Vermeijden HD, et al. Anterolateral ligament reconstruction improves rotational control: a systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2022;30(2):677-687. **LEVEL I**