import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **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 **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% **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 **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 **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 ## 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) ## ACL Anatomy ### Macroscopic Structure - **Origin**: Posteromedial aspect of lateral femoral condyle on lateral wall of intercondylar notch - **Insertion**: Anterior tibial plateau between tibial spines, just anterior to tibial eminence - **Dimensions**: 30-35mm length, 10-12mm width, cross-sectional area 30-50mm² - **Blood supply**: Middle genicular artery (branch of popliteal) - supplies synovial sheath, limited intrinsic healing capacity ### Bundle Anatomy - **Anteromedial (AM) bundle**: Taut in flexion, controls anterior translation and internal rotation, larger bundle (60-70% of ACL) - **Posterolateral (PL) bundle**: Taut in extension, controls hyperextension and internal rotation, smaller bundle (30-40%) - **Single-bundle reconstruction**: Aims to reproduce center of both bundles (anatomic footprint center) ### Femoral Footprint - **Location**: Lateral wall of medial surface of lateral femoral condyle - **Shape**: Elliptical with long axis vertical in extension - **Position**: 10:30 o'clock right knee (1:30 left knee) on lateral wall when viewed through anteromedial portal at 90° flexion - **Landmarks**: Resident's ridge (lateral intercondylar ridge) - anterior border; bifurcate ridge - separates AM/PL; over-the-top position - posterior border - **Center of footprint**: 1-2mm anterior to over-the-top position, high on lateral wall ### Tibial Footprint - **Location**: Anterior tibia, posterior to anterior horn lateral meniscus - **Shape**: Oval with long axis anteroposterior - **Position**: Center is 7mm posterior to anterior edge of tibia, lateral to medial tibial spine - **Landmarks**: Anterior to tibial spine (ACL anterior, PCL posterior), lateral to medial spine ## Biomechanics ### ACL Function - **Primary restraint**: Anterior tibial translation (85% of restraining force at 30° flexion, 90% at 90°) - **Secondary restraint**: Internal rotation of tibia (especially near extension), hyperextension - **Proprioception**: Mechanoreceptors provide sensory feedback for neuromuscular control ### Graft Biomechanics **Native ACL Properties**: - Tensile strength: 2,160 ± 157 N - Stiffness: 242 ± 28 N/mm - Cross-sectional area: 30-50 mm² **4-Strand Hamstring Graft**: - Initial strength: 4,090 ± 295 N (2x native ACL) - Stiffness: 807 ± 75 N/mm - By 12 weeks: 50-60% of native ACL strength (ligamentization process) - By 1 year: 75-80% of native strength - Graft never returns to 100% native ACL properties **BPTB Graft**: - Initial strength: 2,900 ± 300 N - Bone-to-bone healing faster than soft tissue (6-8 weeks vs 12+ weeks) - Stiffness higher due to bone blocks ### Fixation Strength Requirements - **Immediate post-op**: Graft tensioned at 20-30N - **Rehabilitation loads**: Peak forces 400-500N during aggressive rehab - **Normal activities**: 630N walking, 1730N descending stairs - **Fixation target**: >450N initial strength minimum, >800N preferred **Suspensory Cortical Device**: 1,000-1,200N initial strength **Interference Screw** (8mm graft, 9mm screw): 400-600N initial strength ## Graft Harvest Variations ### Standard 4-Strand (ST+G Both Sides) - **Technique**: Harvest both semitendinosus and gracilis, fold each at midpoint creating 4 strands - **Advantages**: Excellent diameter (8-10mm typical), highest strength, gold standard - **Disadvantages**: Harvests 2 tendons, theoretical hamstring weakness (not clinically significant in most studies) ### 5-Strand (ST Only, Preserve Gracilis) - **Technique**: Harvest longer ST (35-40cm), fold to create 5 strands, preserve gracilis - **Advantages**: Maintains gracilis function, adequate diameter if ST sufficient length - **Disadvantages**: May not achieve 8mm diameter in smaller patients, technically demanding ### Tripled Semitendinosus - **Technique**: Long ST folded to create 3 strands - **Advantages**: Single tendon harvest - **Disadvantages**: Often inadequate diameter (<8mm), higher failure rates ## Portal Techniques ### Standard Trans-AM Portal (Gold Standard) - **Femoral drilling**: Through anteromedial portal at 110-120° flexion - **Advantages**: Achieves anatomic femoral tunnel (10:30/1:30), best rotational control - **Disadvantages**: Risk to medial femoral condyle cartilage if poor technique - **Tunnel position**: Can achieve full range of anatomic positions ### Transtibial Technique (Outdated) - **Femoral drilling**: Through tibial tunnel - **Why obsolete**: Cannot achieve anatomic femoral tunnel - forces vertical anterior tunnel (11-12 o'clock), poor rotational control - **Historical note**: Was standard until 2005, now considered suboptimal ### Outside-In Technique - **Femoral drilling**: From lateral cortex of femur into joint - **Advantages**: Excellent femoral tunnel control, minimal cartilage risk - **Disadvantages**: Requires separate lateral incision, less common ### All-Inside Technique - **Method**: Uses retrodrill reamers creating socket tunnels not full tunnels - **Advantages**: No distal femoral/anterior tibial prominence, smaller bone removal - **Disadvantages**: Requires specific instrumentation, less bone-graft interface ## Fixation Variations ### Femoral Fixation Options **Adjustable Cortical Suspensory** (Preferred): - TightRope, ZipLoop, adjustable Endobutton - Allows intraoperative tensioning and length adjustment - Strength >1000N - Concern: Graft-tunnel motion ("windshield wiper effect") - may delay healing **Fixed-Loop Cortical Suspensory**: - Standard Endobutton - Requires pre-measurement of tunnel length - No intraoperative adjustment - Strength >1000N **Interference Screw**: - Bioabsorbable (PLLA, PDLA) or metal (titanium) - Size 7-9mm diameter, 25-30mm length - Aperture fixation promotes healing - Risk: Graft laceration if divergent **Hybrid Fixation** (Increasingly Popular): - Cortical suspensory + interference screw - Combines cortical strength with aperture fixation - Reduces graft-tunnel motion concerns - Higher cost ### Tibial Fixation Options **Interference Screw** (Most Common): - Bioabsorbable preferred (avoids MRI artifact) - 7-9mm diameter, 25-30mm length - Insert parallel to graft, not divergent - Strength 400-600N **Screw and Sheath/Washer**: - Backup fixation over post - 6.5mm AO screw with spiked washer - Risk of prominence **Suspensory** (Rare at Tibia): - TightRope on both ends - Allows adjustment - Less common due to preference for aperture fixation ## Evidence-Based Rehabilitation ### Accelerated vs Traditional Protocols - **Historical**: Delayed weightbearing, prolonged bracing, restricted ROM - **Modern accelerated**: Immediate WBAT, early ROM, no routine bracing - **Evidence**: Multiple RCTs show accelerated protocols have equivalent or better outcomes with faster return to function and lower stiffness rates ## Phase-by-Phase Protocol ### Phase 1: Protection & Early Motion (0-2 Weeks) **Goals**: Control pain/swelling, restore full extension, achieve 90° flexion, quadriceps activation **Weightbearing**: WBAT with crutches (wean as pain allows, typically 5-7 days) **Bracing**: Unlocked hinged brace for comfort only (not mandatory) - remove for exercises, sleep **ROM**: Full extension PRIORITY (achieve by week 2), passive flexion to 90° by week 2 - Prone hangs for extension - Heel slides for flexion - Patellar mobilization **Exercises**: - Quadriceps sets hourly - Straight leg raises (when quad control adequate) - Ankle pumps - Hamstring stretching (gentle) - Ice/elevation **Restrictions**: No active hamstring exercises (protect graft), no pivoting ### Phase 2: Progressive Strengthening (2-6 Weeks) **Goals**: Full ROM (0-130°), normalized gait, progress strengthening **Weightbearing**: Full without aids **ROM**: Should achieve 0-130° by week 6 **Exercises**: - Closed chain: Wall sits, mini squats (0-60°), step-ups, leg press (0-60°) - Cycling (high seat, no resistance initially) - Pool walking (week 4+) - Proprioception: Single leg balance, wobble board - Continue quad emphasis **Restrictions**: No open chain quadriceps (6 weeks), no hamstring strengthening yet, no running/jumping ### Phase 3: Advanced Strengthening (6-12 Weeks) **Goals**: Normalize strength, progress functional activities **ROM**: Full maintained **Exercises**: - Progress closed chain: Squats to 90°, lunges, step downs - Begin open chain quadriceps (week 8-12) - Begin hamstring strengthening (week 8) - Cycling increased resistance - Swimming/water running - Progress proprioception: Perturbation training **Restrictions**: No running until week 12, no agility drills, no contact sports ### Phase 4: Return to Running (12-16 Weeks) **Goals**: Begin running program, sport-specific training **Criteria for progression**: - Full ROM - No effusion - Quadriceps strength >70% LSI - Good single-leg balance - Completed straight-line running progression **Exercises**: - Running progression: Walk-jog, straight-line jog, increase speed, increase distance - Plyometrics: Double-leg jumping, progress to single-leg - Agility: Cutting drills, figure-8 running - Sport-specific drills **Testing**: Isokinetic strength testing at 4 months ### Phase 5: Return to Sport (6-12 Months) **Minimum time**: 9 months (12 months preferred for elite athletes) **Mandatory criteria** (ALL must be met): - Minimum 9 months post-op (6-9 months has 7x higher re-rupture risk) - Quadriceps strength >90% LSI (isokinetic at 60°/sec and 180°/sec) - Hamstring strength >90% LSI - Hop testing >90% LSI (single hop, triple hop, crossover hop, timed hop) - No effusion or pain - Full ROM - Psychological readiness (ACL-RSI score >56) - Sport-specific skills training completed **Progressive RTS**: - Non-contact training - Limited contact practice - Full practice - Competition ## Complications of Poor Rehabilitation **Arthrofibrosis/Stiffness**: - Incidence 2-5% - Risk factors: Delayed extension focus, inadequate early ROM, prolonged immobilization - Prevention: Aggressive early extension focus, no prolonged bracing **Quadriceps Inhibition**: - Common post-ACL (protective mechanism) - Requires focused neuromuscular re-education - Electrical stimulation may help **Premature RTS**: - Single biggest controllable risk factor for re-rupture - RTS <9 months has 7-fold increased risk - Must use objective criteria not just time ## Short-Term Outcomes (0-2 Years) ### Stability Outcomes - **Negative Lachman**: 85-95% at 2 years - **Negative pivot shift**: 80-90% at 2 years - **Side-to-side KT-1000**: <3mm difference in 85-90% - **Subjective stability**: 90-95% satisfied ### Functional Outcomes - **Return to pre-injury activity level**: 65-80% at 2 years - **Return to competitive sport**: 55-65% - **Patient satisfaction**: 85-90% - **IKDC subjective score**: Mean 80-85 (Grade A/B) - **Lysholm score**: Mean 85-90 ## Long-Term Outcomes (5-10+ Years) ### Stability Maintenance - **5-year stability**: 85-90% clinically stable - **10-year stability**: 80-85% clinically stable - Slow deterioration over time from graft elongation/wear ### Degenerative Changes (Osteoarthritis) - **10-year OA rate**: 40-60% radiographic changes - **20-year OA rate**: 70-80% radiographic changes - **Symptomatic OA**: 20-30% at 10 years, 50% at 20 years - **Risk factors**: Age at injury, meniscectomy, cartilage damage, limb alignment - **Important**: OA rate similar whether ACL reconstructed or not - the initial injury creates OA risk ### Sport Participation - **Long-term sport participation**: 50-60% at same level at 10 years - Many quit due to psychological factors not physical limitations ## Failure Rates ### Overall Revision Rates - **2-year revision**: 2-5% - **5-year revision**: 4-8% - **10-year revision**: 5-10% ### Risk Factors for Failure - **Age <20 years**: Relative risk 2-3x (most significant risk factor) - **Male sex**: RR 1.5-2x - **Graft diameter <8mm**: RR 2-3x - **Return to pivoting sport**: RR 2x - **RTS <9 months**: RR 7x - **Non-anatomic tunnel**: RR 2-3x - **Allograft in young patients**: RR 2-4x ## Major Complications ## Graft Choice Specific Issues ### Hamstring Specific - **Hamstring weakness**: Theoretical concern but minimal functional impact in most studies - **Inadequate diameter**: 5-10% cannot achieve 8mm - consider alternative graft - **Graft harvest failure**: Premature amputation 5-10% from accessory bands ### BPTB Specific (Comparison) - **Anterior knee pain**: 30% vs 10% hamstring - **Kneeling pain**: More common and persistent - **Patella fracture**: 0.5-1% risk (intraoperative or late stress fracture) - **Patella tendon rupture**: <0.5% - **Patellar tendinitis**: 5-10% **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. ### 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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.' - 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. **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%).' - 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 **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. ## References 1. 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 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. Leys T, Salmon L, Waller A, Linklater J, Pinczewski L. Clinical results and risk factors for reinjury 15 years after anterior cruciate ligament reconstruction: a prospective study of hamstring and patellar tendon grafts. Am J Sports Med. 2012;40(3):595-605. doi:10.1177/0363546511430375 4. Grassi A, Pizza N, Tedesco D, Zaffagnini S. Clinical outcomes and complications of a collagen meniscus implant: a systematic review. Int Orthop. 2014;38(9):1945-1953. doi:10.1007/s00264-014-2408-9 5. Frobell RB, Roos HP, Roos EM, Roemer FW, Ranstam J, Lohmander LS. Treatment for acute anterior cruciate ligament tear: five year outcome of randomised trial. BMJ. 2013;346:f232. doi:10.1136/bmj.f232 6. Persson A, Fjeldsgaard K, Gjertsen JE, et al. Increased risk of revision with hamstring tendon grafts compared with patellar tendon grafts after anterior cruciate ligament reconstruction: a study of 12,643 patients from the Norwegian Cruciate Ligament Registry, 2004-2012. Am J Sports Med. 2014;42(2):285-291. doi:10.1177/0363546513511419 7. 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 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. Spindler KP, Wright RW. Clinical practice. Anterior cruciate ligament tear. N Engl J Med. 2008;359(20):2135-2142. doi:10.1056/NEJMcp0804745 10. Kyung HS, Kim HJ, Yoo JD, Seo JH, Kim YB. Factors influencing graft rupture after primary ACL reconstruction. Knee Surg Sports Traumatol Arthrosc. 2014;22(9):2046-2052. doi:10.1007/s00167-013-2728-3

ACL Reconstruction - Hamstring Autograft (4-Strand)

ACL Reconstruction - Hamstring Autograft (4-Strand)