import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: Branch of saphenous nerve crosses medial to patellar tendon at joint line level, approximately 1-2cm medial to midline incision **Protection**: Use vertical midline incision (not paramedian). Retract nerve laterally if identified, or accept sacrifice with patient counseling. Transection rate 60% with vertical incision causing anteromedial knee numbness (usually well-tolerated) **Location**: 5-8mm posterior to posterior tibial cortex at level of joint line, tethered by soleus arch and geniculate vessels making it relatively fixed **Protection**: Measure tibial tunnel depth carefully, stop reaming when intra-articular under arthroscopic visualization. Keep tibial tunnel angle 50-60 degrees (not steeper). Avoid posterior cortex blow-out with controlled reaming and finger protection posteriorly **Location**: Directly posterior to tibial tunnel exit point, approximately 7mm posterior to ideal tibial ACL footprint position at junction of middle and anterior thirds **Protection**: Position tibial guide 7mm anterior to PCL insertion. Use 55-degree angle (not steeper than 60 degrees). Watch arthroscopically as reamer emerges and stop immediately when intra-articular. Test PCL integrity after tibial tunnel completion **Location**: Lateral femoral condyle posterior articular cartilage margin at femoral tunnel entry, medial femoral condyle and tibial plateau cartilage during portal placement **Protection**: Position femoral tunnel 6-8mm anterior to posterior cartilage margin (over-the-top position). Preserve 2mm posterior wall. Use soft tissue protection during drilling. Confirm tunnel position before reaming. Avoid cartilage injury during portal placement and instrument manipulation **Location**: Superficial fibers attach 7-8cm distal to joint line on tibia, deep fibers (meniscotibial) at joint line. At risk during anteromedial portal placement if too medial or distal **Protection**: Place anteromedial portal under direct arthroscopic visualization using outside-in technique with spinal needle first. Position portal just medial to patellar tendon at joint line level (not too medial). Use transillumination to avoid MCL if anatomy unclear ## ACL Reconstruction Techniques Classification **By Graft Type:** - **Autograft**: BTB (gold standard), hamstring (quadrupled semitendinosus/gracilis), quadriceps tendon, iliotibial band - **Allograft**: BTB, Achilles, tibialis anterior/posterior - higher failure rates in young active patients (30% vs 10%) - **Synthetic**: Historical only (Gore-Tex, Dacron) - high failure rates, no longer used **By Tunnel Technique:** - **Transtibial**: Femoral tunnel drilled through tibial tunnel - constrains femoral tunnel to non-anatomic vertical position (historical technique) - **Anteromedial Portal**: Independent femoral tunnel positioning through AM portal - anatomic positioning possible (current standard) - **Two-Incision**: Open lateral femoral tunnel drilling - rarely used - **All-Inside**: Short tunnels with cortical suspensory fixation both sides - preserves bone stock for revision **By Fixation Method:** - **Interference Screws**: Metal (titanium) or bioabsorbable (PLLA/PLGA) - bone block compressed against tunnel wall - **Suspensory**: EndoButton, TightRope - graft loop suspended from cortical button - **Hybrid**: Suspensory femoral + interference tibial (common combination) - **Supplemental**: Screw + sheath/washer, screw + suture post tie ## Evidence-Based Graft Selection **BTB Autograft Advantages** (Level 1 Evidence): - Biomechanical strength 168% native ACL vs 120% quadrupled hamstring - Bone-to-bone healing 6-8 weeks vs 12+ weeks soft tissue-to-bone - Lower failure rates in patients under 25 years (8% vs 15% hamstring) - Gold standard with longest track record (over 40 years) - Superior outcomes in high-demand pivoting sports **BTB Autograft Disadvantages**: - Anterior knee pain 10-30% vs 5% hamstring (most common long-term complaint) - Kneeling discomfort in up to 50% of patients - Patellar fracture risk 0.3-1% (intraoperative or stress fracture) - Patellar tendon rupture less than 1% if proper technique (keep residual tendon over 17mm) - Donor site morbidity with patellofemoral symptoms **Hamstring Autograft** (Quadrupled Semitendinosus/Gracilis): - Lower anterior knee pain (5% vs 10-30% BTB) - Smaller cosmetic incision - Higher failure rates in young athletes under 25 (15% vs 8%) - Potential hamstring weakness (10-15% flexion strength deficit) - Slower incorporation (soft tissue-to-bone healing 12+ weeks) **Allograft Considerations**: - Avoid in patients under 25 years (failure rate 30% vs 10% autograft) - Acceptable in older, lower-demand patients over 40 years - Advantages: no donor site morbidity, shorter operative time, less pain - Disadvantages: disease transmission risk (very low with modern screening), slower incorporation, higher failure rates, increased cost ## Native ACL Anatomy **Bundles and Function**: - **Anteromedial (AM) Bundle**: Tightens in flexion, primary restraint to anterior translation at 90 degrees flexion - **Posterolateral (PL) Bundle**: Tightens in extension, primary restraint in extension and rotational control - Combined footprint area: 113 square mm (femoral), 137 square mm (tibial) - Single-bundle reconstruction approximates AM bundle function primarily **Femoral Attachment**: - Posterior lateral wall of intercondylar notch - Anatomic landmarks: Resident's Ridge (anterior margin), bifurcate ridge (between AM/PL), deep cartilage (superior), over-the-top position (posterior) - Clock-face position: 10:30 left knee, 1:30 right knee for center of footprint - Footprint shape: elliptical, oriented in line with femoral shaft **Tibial Attachment**: - Anterior intercondylar area of tibial plateau - 7mm anterior to PCL insertion (key landmark) - Medial to lateral tibial spine (center of footprint) - Junction of middle and anterior thirds in sagittal plane - Footprint shape: broader and more circular than femoral ## Biomechanical Principles **Graft Strength Comparison** (Ultimate Tensile Load): - Native ACL: 2160N (baseline 100%) - BTB autograft 10mm: 2900N (168% of native) - Quadrupled hamstring: 4090N initially but only 2500N (120%) after preparation - Quadriceps tendon: 2352N (109%) - Native patellar tendon: 3200N before harvest **Healing Phases**: - **Weeks 0-4**: Inflammatory phase, graft weakest (30-40% initial strength) - **Weeks 4-12**: Proliferation and revascularization (ligamentization process) - **Months 3-6**: Remodeling, gradual strength increase to 40-50% - **Months 6-12**: Maturation, strength 60-70% at 1 year - **Years 1-2**: Continued remodeling, final strength 60-80% of native (never reaches 100%) **Tunnel Position and Kinematics**: - Anatomic positioning (10:30/1:30) recreates near-isometric behavior through ROM - Vertical femoral tunnel (transtibial technique) creates non-anatomic over-constraint in extension - Tibial tunnel too anterior causes roof impingement and loss of flexion - Tibial tunnel too posterior risks PCL injury and creates over-constraint in flexion **Fixation Biomechanics**: - Interference screw provides strongest initial fixation (500-700N) - Suspensory fixation: 400-500N but allows graft motion (bungee effect) - Bone-to-bone healing: 6-8 weeks (BTB) vs 12+ weeks soft tissue-to-bone (hamstring) - Fixation location: femoral side is weakest link initially, tibial side after incorporation ## Femoral Tunnel Drilling Approaches **Anteromedial Portal Technique** (Current Gold Standard): - Advantages: Independent tunnel positioning, anatomic placement possible, better rotational control - Technique: Flex knee 90-110 degrees, drill through AM portal (or accessory far AM portal) - Position: 10:30/1:30 clock-face, 3-4mm distal to Resident's Ridge - Challenges: Requires hyperflexion, potential for short tunnel if poor positioning - Success rate: 85-90% good-excellent outcomes vs 70-75% transtibial **Transtibial Technique** (Historical): - Advantages: Technically easier, single tunnel drilling guide - Technique: Femoral tunnel drilled through tibial tunnel - Position: Constrained to 11-12 o'clock position (vertical, non-anatomic) - Disadvantages: Non-anatomic vertical graft, increased failure rates (25-30% vs 10-15%), poor rotational control - Current use: Generally abandoned in favor of AM portal technique **Two-Incision Technique**: - Technique: Open lateral femoral approach with inside-out drilling - Indication: Revision cases with medial femoral condyle bone loss - Rarely used with modern arthroscopic techniques **Outside-In Technique**: - Technique: Femoral guide pin placed percutaneously, drilled outside-in - Advantages: Easy to achieve anatomic position - Disadvantages: Risk of cartilage injury, short tunnel length - Limited current use ## Fixation Method Variations **Interference Screw Fixation**: - **Metal (Titanium)**: Strongest fixation (700N), causes MRI artifact, permanent - **Bioabsorbable (PLLA/PLGA)**: Avoid MRI artifact, weaker (500-600N), risk of inflammatory reaction (5-10%), cyst formation (5%), incomplete resorption - **Technique**: Screw diameter 1mm larger than tunnel for compression, placed anterior to graft (divergent position) - **Pearls**: Watch for screw divergence (tracking outside tunnel), ensure bone-to-bone compression **Suspensory Fixation (EndoButton/TightRope)**: - **Advantages**: Preserves bone stock (revision friendly), allows graft adjustability - **Disadvantages**: Graft motion/bungee effect (1-3mm), requires drill through far cortex, potential button flip - **Technique**: Measure femoral condyle thickness (usually 35-40mm), drill completely through, flip button on lateral cortex - **Best for**: All-inside techniques, revision surgery, bone preservation **Hybrid Fixation**: - Suspensory femoral + interference screw tibial (very common combination) - Advantages: Strong fixation both ends, some bone stock preservation - Technique: Fix femoral side first with button, tension graft, fix tibial with screw **Supplemental Fixation**: - Screw + suture post tie-down: Extra security for high-demand athletes - Screw + sheath/washer: Distributes force, prevents bone block pull-through - Indications: Revision cases, poor bone quality, very high-demand athletes ## Graft Preparation Variations **Standard BTB Preparation**: - 10mm bone blocks, 25-30mm length - Cylindrical shaping with rongeur and rasp - 2.0mm drill holes for suture passage **Press-Fit Technique**: - Bone blocks sized 1mm larger than tunnels - No interference screw needed - Relies on press-fit friction for initial fixation - Limited current use **Bone Block Size Variations**: - **Standard**: 10mm diameter matching tunnel - **Undersized femoral**: 9mm femoral block for easier passage (some surgeons) - **Oversized**: 11mm blocks for press-fit (rarely used) ## Expected Outcomes **Return to Sport** (Level 1 Evidence): - 85-90% return to any sport by 12 months - 65-75% return to pre-injury level of competition - 55-65% return to elite competitive level - Timing: Minimum 9 months, ideally 12+ months (return before 9 months doubles re-rupture risk) **Knee Stability**: - 90-95% achieve grade 0-1 Lachman at 2 years - 85-90% negative pivot shift at 2 years - 5-10% persistent grade 2 laxity despite intact graft (usually asymptomatic) - 5-10% graft failure requiring revision **Patient Satisfaction**: - 85-90% satisfied or very satisfied at 2 years - 75-80% would undergo procedure again - Anterior knee pain is most common reason for dissatisfaction with BTB **Long-Term Outcomes (10+ years)**: - 50-70% develop radiographic osteoarthritis changes - Meniscus status is strongest predictor (meniscectomy increases OA risk 3-fold) - Graft survival: 85-90% at 10 years, 80-85% at 15 years - Functional outcomes remain good despite radiographic changes ## Complications - Detailed Analysis **Additional Complications**: - **Patellar Tendon Rupture**: Less than 1% if proper technique (residual tendon over 17mm). Repair urgently if occurs. Devastating complication requiring allograft reconstruction usually. - **Saphenous Nerve Injury**: 60% subclinical, 10-15% symptomatic numbness anteromedial knee. Usually resolves partially over 6-12 months. Neuroma formation rare (less than 2%), may require excision. - **Vascular Injury**: Popliteal artery injury 0.1-0.5% (posterior cortex blowout, aggressive reaming). Recognize by expanding hematoma, loss of distal pulses. Requires immediate vascular surgery consultation, repair or bypass. High amputation risk (20-30%) if delayed. - **Cyclops Lesion**: 5-10%, fibrous nodule from ACL remnants impinging in notch causing extension loss. Diagnosis: MRI shows anterior nodule. Treatment: Arthroscopic excision, usually excellent result. - **Heterotopic Ossification**: 5-10% develop bone formation in tunnels or soft tissues. Usually asymptomatic. May cause stiffness if severe. Treatment: Observation if asymptomatic, excision if symptomatic after maturation (12+ months). - **Donor Site Morbidity**: Kneeling pain (50%), patellofemoral symptoms (20-30%), quadriceps weakness (10-15%). Most improve over 1-2 years. Permanent in 10-15% of patients. ## Phase 1: Protection (Weeks 0-2) **Goals**: Protect graft, control pain and swelling, initiate ROM, activate quadriceps **Weight-Bearing**: WBAT with crutches for comfort (typically 1-2 weeks) **Brace**: Hinged brace locked in extension for sleep and ambulation first week, then unlocked 0-90 degrees **ROM**: - Passive extension to 0 degrees immediately (heel props, prone hangs) - Active-assisted flexion 0-90 degrees by week 1 - Progress to 0-120 degrees by week 2 - CRITICAL: Full extension by week 2 to prevent arthrofibrosis **Exercises**: - Quadriceps sets (isometric at 0 degrees) - Straight leg raises (when quad control achieved) - Ankle pumps, calf stretches - Patellar mobilization (all directions) - Stationary bike (no resistance) when 110 degrees flexion achieved **Restrictions**: No running, jumping, pivoting. No hamstring exercises first 6 weeks (protective for ACL). Avoid kneeling on donor site. ## Phase 2: Intermediate (Weeks 2-12) **Goals**: Full ROM, normalize gait, progressive strengthening, proprioception **Weight-Bearing**: Full without assistive devices by week 2-3 **ROM**: Full ROM (0-135 degrees) by week 4-6 **Strengthening** (Emphasis on closed-chain): - Leg press (90-30 degrees only, avoid terminal extension first 6 weeks) - Step-ups and step-downs (progress height) - Single-leg balance and proprioception drills - Wall sits and mini-squats (0-60 degrees) - Pool exercises (buoyancy-assisted) - Bike, elliptical (low resistance progressing) **Weeks 6-12**: - Double-leg squats progressing to single-leg - Leg press full ROM - Hamstring strengthening (now permitted after 6 weeks) - Core and hip strengthening - Light resistance stationary bike **Criteria to Progress**: Full ROM, minimal effusion, quad strength 70% contralateral, normal gait ## Phase 3: Advanced Strengthening (Months 3-6) **Goals**: Restore strength, begin running program, sport-specific training **Running**: - Initiate when quad strength 80% contralateral (usually month 3-4) - Start with straight-line jogging on treadmill - Progress distance before speed - Graduate to outdoor running by month 4-5 **Strengthening**: - Olympic lifts (deadlifts, squats, cleans) - Plyometrics (box jumps, single-leg hops) - Agility drills (cutting, pivoting in controlled environment) - Sport-specific movements **Criteria to Progress**: Quad/hamstring strength 85% contralateral, negative hop test asymmetry (less than 10%), confident with cutting ## Phase 4: Return to Sport (Months 6-12) **Goals**: Full athletic function, safe return to competition **Clearance Criteria** (ALL must be met): - **Time**: Minimum 9 months from surgery (ideally 12+ months) - **Strength**: Quadriceps and hamstring 90% or more of contralateral - **Hop Testing**: Single-leg hop, triple hop, crossover hop all within 90% of contralateral - **Functional Tests**: ACL-RSI (psychological readiness) score over 60, confidence with cutting/pivoting - **Clinical Exam**: Negative Lachman (grade 0-1), negative pivot shift, full ROM **Return to Sport Protocol**: - Month 6-7: Practice with team (no contact) - Month 7-8: Full practice participation - Month 9: Clearance for competition if criteria met - Month 9-12: Graduated return (limited minutes/games initially) **Brace for Sport**: - Functional ACL brace: No proven benefit for graft protection - May provide psychological confidence - Individual decision based on patient preference **Prevention of Contralateral Injury**: - ACL injury prevention program for contralateral knee (FIFA 11+, PEP program) - Risk of contralateral ACL tear: 10-15% within 2 years - Higher risk in young athletes (20-25% under age 18) **Patient Position**: Supine with thigh tourniquet at groin level. Leg holder (allows flexion/extension throughout procedure) or lateral thigh post at mid-thigh level. Foot of bed dropped to allow knee hyperflexion to 110-120 degrees (needed for femoral tunnel visualization). Contralateral leg in lithotomy or abducted to allow fluoroscopy if used. **Surgical Approach**: Arthroscopic with anteromedial and anterolateral portals, plus limited open anterior midline incision (6-8cm vertical) for bone-patellar tendon-bone autograft harvest **Equipment**: Standard knee arthroscopy set, ACL guide system (55-degree tibial guide, femoral offset guide for AM portal), cannulated reamer set (7-11mm), interference screws (metal or bioabsorbable, 7-12mm diameter, 20-35mm length), oscillating saw for bone block harvest, graft preparation board, tensioning device or manual tension assessment **Incision**: Vertical midline incision from inferior pole of patella extending 6-8cm distally toward tibial tubercle for graft harvest. Standard arthroscopic portals: anterolateral (diagnostic viewing), anteromedial (working portal and femoral tunnel access) ### Step 1: Examination under anaesthesia and diagnostic arthroscopy Examination under anaesthesia and diagnostic arthroscopy: After induction of anesthesia and before tourniquet inflation, perform comprehensive examination of both knees for comparison. Lachman test at 20-30 degrees flexion (most sensitive test, normal less than 3mm side-to-side difference, grade 1 is 3-5mm, grade 2 is 6-10mm, grade 3 is over 10mm). Anterior drawer test at 90 degrees flexion. Pivot shift test (most specific for functional instability, grade 0 negative to grade 3 marked subluxation-reduction clunk). Test medial and lateral collateral ligaments, posterolateral corner, posterior cruciate ligament. Document all findings in operative note for medicolegal purposes. Prepare and drape leg circumferentially. Exsanguinate with Esmarch bandage and inflate tourniquet to 300mmHg (or 100mmHg above systolic). Establish anterolateral portal first using outside-in technique with spinal needle to confirm position, then make 5mm vertical skin incision and insert arthroscope. Perform systematic 15-point diagnostic arthroscopy: suprapatellar pouch (adhesions, synovitis), patellofemoral joint (tracking, chondromalacia), medial gutter, medial compartment (meniscus anterior horn to posterior horn, cartilage surfaces, medial tibial plateau), intercondylar notch (ACL/PCL integrity), lateral compartment (meniscus, cartilage, lateral plateau), lateral gutter. Confirm ACL rupture pattern (complete vs partial, acute vs chronic with meniscoid remnant). Assess for meniscal tears especially posterior horn lateral meniscus and ramp lesions (peripheral posterior horn medial meniscus tear, present in 15-20%). Document chondral injuries using ICRS grading. Identify any other ligamentous injuries requiring treatment. **Technical Tip**: EXAM KEY: Pivot shift is the GOLD STANDARD clinical test for functional instability - grade 2-3 is absolute indication for reconstruction in active patients willing to modify activity. The test is positive in 98% of complete ACL tears under anesthesia versus only 35% in clinic due to guarding. Always examine BOTH knees - normal baseline laxity varies significantly between patients (some have constitutional laxity with 5-8mm normal Lachman). Document examination under anesthesia findings thoroughly in operative note. Look specifically for RAMP LESIONS by probing posteriorly in posteromedial gutter - these peripheral medial meniscus tears are present in 15-20% of ACL ruptures and easily missed on standard arthroscopy. The meniscotibial ligament attachment must be probed to identify these. Missing a ramp lesion leads to persistent instability despite successful ACL reconstruction. - Missing combined ligament injuries (PLC, MCL grade 3) - leads to persistent instability despite ACL reconstruction - Overlooking ramp lesion requiring repair - causes persistent giving way and early failure - Portal placement too medial injuring MCL - use spinal needle first to confirm safe trajectory - Aggressive probing causing iatrogenic chondral or meniscal injury ### Step 2: Address concomitant meniscal and chondral pathology FIRST Address concomitant meniscal and chondral pathology FIRST before ACL reconstruction: Repair any meniscal tears using inside-out, outside-in, or all-inside techniques depending on tear location and pattern. Posterior horn repairs are critical to preserve as meniscus is vital for long-term knee health - meniscectomy increases contact pressures by 200-300% and accelerates arthritis (50% develop radiographic OA at 10 years with meniscectomy vs 15% with intact meniscus). Use vertical mattress sutures for peripheral tears in vascular red-red or red-white zones (outer 3-4mm). All-inside devices (FasT-Fix, Sequent) convenient for posterior horn. Ramp lesions require posteromedial portal or trans-septal approach for suture placement - reduce meniscus to capsule and secure with vertical sutures. Debride or microfracture chondral lesions as indicated per standard protocols. If partial meniscectomy required, remove only unstable torn tissue conservatively using basket punch - preserve meniscal rim and anterior/posterior roots. Clear intercondylar notch of soft tissue and ACL remnants using motorized shaver and radiofrequency ablation probe - complete debridement is essential for graft visualization and to prevent cyclops lesion, but preserve remnant vascularity near tibial insertion if possible (enhanced healing potential). Perform notchplasty if needed to visualize lateral wall for femoral tunnel - remove bone from ANTERIOR aspect of intercondylar notch using burr or aggressive shaver, preserving Resident's Ridge as landmark (do not notchplasty posterior wall as this destroys landmarks). Address any adhesions or scar tissue causing limitation of extension BEFORE proceeding with graft placement - knee MUST have full passive extension or cyclops formation and arthrofibrosis inevitable. **Technical Tip**: EXAM KEY: Meniscal preservation is CRITICAL for long-term outcomes - meniscectomy increases contact pressures 2-3 fold and accelerates post-traumatic arthritis development. ALWAYS attempt repair in young patients even for tears that appear marginal. Studies show 80-85% repair healing rates when combined with ACL reconstruction (enhanced healing from knee hemarthrosis and marrow stimulation). Ramp lesions are found by PROBING posteriorly in posteromedial gutter with knee in figure-4 position - you must look for them specifically as they're not visible on standard medial compartment viewing. The meniscotibial ligament separates from capsule. Failure to address extension deficits preoperatively leads to cyclops lesion formation (10% incidence) and arthrofibrosis (5-10%). The knee MUST achieve full passive extension (0 degrees) before proceeding with reconstruction - if limited, aggressive lysis of adhesions and anterior interval release required. Do not accept 5-10 degree flexion contracture thinking it will resolve postoperatively - it will not and leads to disaster. - Inadequate notch debridement causing graft impingement on roof - leads to graft abrasion and failure - Missing ramp lesion (leads to persistent instability in 15-20% of cases) - Excessive meniscectomy - accelerates arthritis, poor long-term outcomes - Proceeding with reconstruction despite flexion contracture - inevitable arthrofibrosis ### Step 3: Bone-patellar tendon-bone graft harvest Bone-patellar tendon-bone graft harvest: Make vertical midline incision from inferior pole of patella extending 6-8cm distally toward tibial tubercle (midline is critical - paramedian increases nerve injury and complication rates). Incise skin and subcutaneous tissue using electrocautery for hemostasis. The infrapatellar branch of saphenous nerve usually crosses medial to patellar tendon at joint line level, 1-2cm medial to midline - identify if possible and retract medially, or accept sacrifice with patient pre-counseling (60% transection rate with vertical incision causing anteromedial numbness which is usually well-tolerated). Expose central third of patellar tendon sharply, incising peritenon. Using ruler and marking pen, carefully measure total patellar tendon width (typically 28-32mm). Mark 10mm width of central patellar tendon - this is CRITICAL, must leave adequate tendon on both sides. Mark 20-25mm length of bone blocks at inferior pole of patella and tibial tubercle insertion (measured perpendicular to tendon). Using oscillating saw with narrow blade, harvest patellar bone block first: make two parallel longitudinal cuts 10mm apart, 10mm deep initially, gradually deepening to 20-25mm total depth. Make transverse base cut connecting the two longitudinal cuts. Use thin curved osteotome gently to complete bone block harvest, directing force posteriorly away from articular surface. Remove bone block and inspect - should be rectangular prism approximately 10mm wide, 10mm anterior-posterior depth, 20-25mm length. Harvest tibial bone block using identical technique. Using #10 blade, sharply incise marked tendon margins on both sides, cutting through peritenon and into tendon substance. Verify residual tendon width on each side - MUST be at least 8-9mm each side (total residual 17mm minimum, preferably 20mm) to prevent rupture risk. Use heavy Mayo scissors or knife to separate central tendon from underlying fat pad anteriorly, taking care to get clean tissue plane. Free tendon proximally and distally to bone blocks. Extract complete bone-tendon-bone graft and place on back table in saline-soaked sponge. Measure final graft dimensions: should be approximately 10mm wide, 50-60mm bone-to-bone length, bone blocks 20-25mm each. **Technical Tip**: EXAM KEY: NEVER take more than ONE-THIRD width of patellar tendon - this is most critical step to prevent patellar tendon rupture. Measure total width first (usually 28-32mm in adults), then take 10mm leaving 18-22mm total residual. Studies show rupture risk increases exponentially if residual tendon less than 17mm (0.5% if over 17mm vs 8% if less than 17mm). Bone block length 20-25mm is optimal - longer blocks (over 25mm) significantly increase patellar fracture risk due to stress riser effect, shorter blocks (less than 20mm) have inadequate fixation strength (only 1-2 screw threads engaged). The infrapatellar nerve WILL be transected in 60% of cases with vertical midline incision - counsel patients preoperatively about anteromedial numbness. Use OSCILLATING SAW not hand saw or osteotome for bone block cuts - this prevents fracture propagation into patella or tibial tubercle (fracture risk 5% with osteotome vs 0.5% with oscillating saw). Create bone blocks with smooth rounded edges, not sharp corners which act as stress risers causing intraoperative or postoperative fracture. Verify bone block dimensions before proceeding - too large will not pass through tunnels, too small will toggle and fail. - Taking greater than 1/3 tendon width - rupture risk 8-fold increase (residual must be over 17mm) - Bone block too long (over 25mm) - stress riser causing patellar or tibial tubercle fracture - Aggressive osteotome use - propagates fractures into patella or tubercle - Saw blade directed anteriorly - violates patellar articular surface causing chondral injury - Inadequate fat pad separation - harvesting fat with tendon creates bulky graft that won't pass ### Step 4: Graft preparation on back table Graft preparation on back table: Shape bone blocks to cylindrical form using rongeur and rasp - target 10mm diameter to match tunnel reamers (verify with sizing cylinder from instrument set). Ensure smooth contours without sharp edges, corners, or irregularities that could cause stress concentrations or difficulty with tunnel passage. Round all edges carefully. Using 2.0mm drill bit, create hole in apex of each bone block for suture passage - position hole centrally to prevent eccentric loading and bone block splitting when sutures tensioned. Pass heavy non-absorbable braided suture (#2 or #5 Ethibond or FiberWire) through drill holes using Keith needle. Tie sutures securely with multiple square knots (minimum 4 throws). These sutures will be used for graft passage and can provide supplemental fixation if needed. Create whipstitch on tendon ends using same suture material for additional graft control during passage. Measure final graft dimensions precisely: bone blocks should be 10mm diameter (or 9mm if undersizing femoral block), 20-25mm length, tendon 10mm wide, total bone-to-bone length 50-60mm. Remove all loose tissue, cartilage, and soft tissue tags from bone blocks using rongeur - want clean cortical bone surface for healing. Keep graft moist with saline-soaked sponge throughout preparation and during case - desiccation reduces tensile strength by 30-40%. Size tunnel reamers to match graft - typically 10mm for both femoral and tibial tunnels (some surgeons use 9mm femoral for easier passage). Pre-tension graft by pulling firmly on both sutures simultaneously for 2-3 minutes - this reduces graft creep during tensioning later. Mark graft orientation with marking pen if desired to prevent twisting during passage. **Technical Tip**: EXAM KEY: Graft preparation is critical step - poorly shaped bone blocks will not seat properly in tunnels causing graft elongation, toggle, and failure. The bone blocks MUST be perfectly CYLINDRICAL not rectangular in cross-section - use rasp to smooth all edges and verify with sizing cylinder. Rongeur away any irregularities that could prevent smooth passage. Drill holes in bone centrally to prevent splitting when sutures are tensioned during passage - eccentric holes cause asymmetric loading and fracture through drill hole. Use heavy non-absorbable suture (#2 Ethibond or #5 FiberWire) for passage - absorbable sutures can fail during passage if high tension required. Keep graft moist throughout case in saline-soaked sponge - desiccation reduces graft ultimate tensile strength by 30-40% (from 2900N to less than 2000N). Many surgeons pre-tension the graft by pulling firmly on sutures for 2-3 minutes to 'stretch' it and reduce creep - this can reduce graft elongation by 2-3mm during later cycling. Total graft length bone-to-bone typically 50-60mm (25mm patellar block, 25mm tibial block, 0-10mm tendon between blocks after compression). Some surgeons measure and record exact graft length for comparison postoperatively if failure occurs. - Sharp bone block edges or irregular shape - won't seat in tunnel, gets stuck during passage - Eccentric drill hole placement - bone block fracture through drill hole during passage - Allowing graft to desiccate on back table - reduces strength by 30-40% - Using absorbable suture for passage - suture failure and dropped graft in joint - Bone blocks too large - won't pass through tunnels, or tunnel must be reamed larger ### Step 5: Tibial tunnel preparation - positioning Tibial tunnel preparation - positioning: Switch arthroscope to anteromedial portal for best visualization of tibial ACL footprint. Position tibial guide at anatomic ACL tibial footprint - this is 7mm ANTERIOR to PCL tibial insertion (most reliable landmark), centered between medial and lateral tibial spines in coronal plane, at junction of middle and anterior third of tibia in sagittal plane. The ideal position is just MEDIAL to lateral tibial spine, which represents center of native ACL tibial footprint. Use 55-degree guide in sagittal plane as standard starting point (acceptable range 50-60 degrees) - steeper angle (over 60 degrees) risks short tunnel length, posterior cortex blowout, and PCL injury; shallower angle (less than 50 degrees) risks anterior cortex blowout, graft impingement on intercondylar roof, and short tunnel length. The guide should exit anterior tibial cortex 3-4cm distal to joint line, medial to tibial tubercle (just medial to patellar tendon). Confirm intra-articular starting position arthroscopically before advancing guide pin - the tip should be at the anatomic center of the native ACL tibial footprint. The footprint is elliptical, oriented anteromedial to posterolateral, with center point 7mm anterior to PCL. Verify position from both anteromedial and anterolateral viewing portals. Place guide pin and overdrill with cannulated drill or mark position with K-wire before removing guide. **Technical Tip**: EXAM KEY: Tibial tunnel position is CRITICAL determinant of outcome - too anterior causes graft impingement on intercondylar roof and loss of flexion (roof impingement syndrome), too posterior injures PCL or risks posterior cortex blowout with popliteal injury. The KEY LANDMARK is 7mm ANTERIOR to PCL insertion and MEDIAL to lateral tibial spine. Some surgeons use 'over-the-top of lateral spine' as landmark. Use 55-degree guide as standard (good compromise between adequate tunnel length 35-40mm and avoiding PCL) - range 50-60 degrees acceptable. Confirm position arthroscopically from BOTH portals before drilling - what looks good from one portal may be malpositioned when viewed from other angle. The 'Resident's Ridge' is the FEMORAL landmark (anterior edge of femoral ACL footprint), don't confuse with tibial positioning. Check that exit point is 3-4cm below joint line - if too distal (over 5cm), tunnel will be too vertical leading to short intra-articular length and potential graft-roof impingement. Many surgeons use intraoperative fluoroscopy to verify tibial tunnel angle on lateral view before reaming (50-60 degrees from tibial plateau). - Position too posterior - PCL injury, posterior cortex blowout with popliteal vessel injury (0.1-0.5%) - Position too anterior - roof impingement, graft abrasion, loss of flexion, eventual failure - Angle too steep (over 60 degrees) - short tunnel length (less than 30mm) with inadequate fixation - Exit point too distal - vertical tunnel causing impingement and biomechanical failure ### Step 6: Tibial tunnel drilling and preparation Tibial tunnel drilling and preparation: Drive guide pin from anterior tibia through tibial footprint position, confirming intra-articular position arthroscopically before advancing pin fully - tip should emerge at center of footprint, 7mm anterior to PCL. Measure pin length with depth gauge to determine tunnel length (typically 35-45mm intra-articular). Select cannulated reamer size matching graft (typically 10mm for 10mm bone block). Ream tibial tunnel over guide pin using cannulated reamer, drilling from anterior to posterior (outside-in direction) to prevent posterior cortex blowout. Assistant protects posterior soft tissues by placing finger posterior to tibia. Advance reamer slowly, watching arthroscopically as reamer emerges into joint - STOP immediately when reamer is fully intra-articular to avoid PCL injury or posterior cortex penetration. Remove reamer over guide pin, then remove pin. Clear tunnel aperture of debris and bone using arthroscopic shaver and curette - ensure clean surface for bone block seating. Use rasp or motorized burr to chamfer and smooth anterior rim of tibial tunnel entrance - this is CRITICAL as sharp edges will act like knife sawing through graft over time causing abrasion and failure. Create smooth beveled edge, removing 2-3mm of bone from anterior rim circumferentially. Test tunnel with probe - should be smooth without sharp edges. Pass curved suture grasper (or braided suture passing wire) through tibial tunnel from anterior to posterior, retrieve through anteromedial portal, and secure for later graft passage. **Technical Tip**: EXAM KEY: Ream SLOWLY watching arthroscopically throughout - when reamer teeth enter joint space, STOP immediately to avoid PCL injury or posterior cortex penetration. The most common technical error is drilling too far posteriorly injuring PCL or creating posterior cortex blowout (5-8mm to popliteal vessels). Have assistant protect posteriorly with finger to feel reamer emergence. ALWAYS chamfer the tibial tunnel aperture edges generously - sharp corners will act like saw on the graft causing abrasion failure (seen in 10-15% of failures as 'windshield wiper' sign on MRI). The tunnel should be minimum 30mm intra-articular length for adequate interference screw fixation (need 20-25mm screw length). Measure tunnel depth with depth gauge and record. Some surgeons dilate tunnel aperture with larger reamer (11mm for 10mm tunnel) to reduce graft kinking at aperture - 'socket' technique reduces stress concentration at tunnel entrance. Ensure debris is cleared completely - bone chips prevent proper bone block seating and can cause tunnel widening. Save bone chips for potential bone grafting if needed. - Reaming too far posteriorly - PCL injury (test PCL after tibial tunnel completion) - Posterior cortex blowout - popliteal neurovascular injury (0.1-0.5% incidence, devastating) - Sharp tunnel aperture edges - graft abrasion and failure ('windshield wiper' lesion) - Tunnel too short (less than 30mm) - inadequate fixation, screw penetrates joint - Inadequate debris removal - prevents bone block seating, causes tunnel widening ### Step 7: Femoral tunnel preparation - anteromedial portal technique Femoral tunnel preparation - anteromedial portal technique: Flex knee to 90-110 degrees (hyperflexion improves visualization of posterior lateral wall). Switch arthroscope back to anterolateral portal for visualization. Through anteromedial portal (or accessory far anteromedial portal if needed for better access), identify anatomic femoral ACL footprint landmarks on lateral wall of intercondylar notch: Resident's Ridge (bony prominence marking ANTERIOR margin of native ACL footprint), deep cartilage margin (superior boundary), bifurcate ridge if present (between anteromedial and posterolateral bundles), over-the-top position (posterior margin where lateral wall transitions to roof). Perform notchplasty if needed to visualize posterior lateral wall - use burr or shaver to remove bone from ANTERIOR aspect of notch (widening the notch), carefully preserving Resident's Ridge as critical landmark (do not notchplasty posterior wall as this removes landmarks and is unnecessary). Position femoral offset guide through anteromedial portal (allows independent femoral tunnel positioning unlike transtibial technique which constrains tunnel). Place guide tip at anatomic footprint position: using clock-face orientation (12 o'clock is superior with knee in 90 degrees flexion), position at 10:30 for left knee or 1:30 for right knee (NOT 11:00/1:00 which is too anterior and vertical), 6-8mm ANTERIOR to posterior articular margin (over-the-top position), 3-4mm DISTAL (posterior) to Resident's Ridge. The guide should aim to preserve 2mm posterior cortex bone bridge (measure on guide). Set guide offset typically 6-8mm (short offset) for AM portal technique. Insert guide pin through guide, checking depth - pin should penetrate lateral femoral cortex. Confirm position is anatomic by viewing from multiple angles, checking offset measurements, and verifying 2mm posterior wall preservation. **Technical Tip**: EXAM KEY: Anteromedial portal technique is SUPERIOR to transtibial technique (Level 1 evidence) - it allows anatomic independent femoral tunnel positioning whereas transtibial constrains femoral tunnel to non-anatomic vertical position (11-12 o'clock) leading to increased failure rates (25-30% vs 10-15% AM portal). The anatomic position is 10:30/1:30 on clock face (reproducing native ACL center) - NOT 11:00/1:00 which is too anterior and vertical. Must preserve 2mm POSTERIOR WALL (lateral cortex) or risk blowout - measure on guide before drilling. If posterior wall less than 2mm, reposition guide more anterior or shallower. Resident's Ridge marks ANTERIOR margin of native ACL footprint - tunnel should be 3-4mm distal/posterior to this ridge. The bifurcate ridge (if visible) separates AM and PL bundles - center of footprint is just posterior to bifurcate ridge. Notchplasty is often needed (60-70% of cases) to visualize posterior wall adequately - remove bone from ANTERIOR notch roof, not posterior wall. Flex knee to 110-120 degrees for best visualization of posterior structures - less flexion (90 degrees) makes posterior wall difficult to see. Consider accessory anteromedial portal placed more medial and proximal for better access angle if standard AM portal trajectory is difficult. - Position too anterior (11:00/1:00) - vertical graft orientation, over-constraint, increased failure 2-fold - Posterior wall blowout (less than 2mm) - loss of fixation, graft elongation and failure - Injuring posterior lateral femoral condyle articular cartilage with drill - causes chondral defect - Malposition not recognized - graft will be non-isometric leading to failure - Notchplasty of posterior wall - removes landmarks, difficult to position tunnel correctly ### Step 8: Femoral tunnel reaming and preparation Femoral tunnel reaming and preparation: Ream femoral tunnel over guide pin using cannulated reamer sized to match graft (typically 10mm for 10mm bone block). Drilling method depends on fixation choice: For INTERFERENCE SCREW fixation, create blind tunnel 25-30mm depth (bone block length 20-25mm plus 5mm extra) - do NOT penetrate lateral femoral cortex far wall. For SUSPENSORY fixation (EndoButton), must drill completely through lateral cortex - measure femoral condyle thickness first with guide pin depth markings (usually 35-40mm), then ream to measured depth plus 5mm to ensure complete cortex penetration. Use depth gauge marked on drill chuck to control depth precisely - STOP when target depth reached. Remove reamer carefully over guide pin to prevent posterior wall damage. If using suspensory fixation, verify far cortex perforation by passing looped wire through tunnel and out lateral cortex. Remove guide pin. Clear tunnel of debris using curette and shaver. Ensure tunnel aperture is clean, smooth, and rounded using curette - remove any sharp edges or irregularities. Check bone quality in tunnel - should be hard subchondral/metaphyseal bone (excellent in femur). If cystic changes present, consider longer tunnel or supplemental fixation. Confirm tunnel position is anatomic by viewing from multiple arthroscopic angles - should recreate native ACL position. From anterolateral viewing, tunnel should be visible on posterior lateral wall at 10:30/1:30 position. From anteromedial viewing, tunnel should not be visible (too posterior). Test tunnel with probe to ensure smooth contours and adequate depth. If position is not anatomic, must decide whether to accept, revise (bone graft and redrill), or abort case. **Technical Tip**: EXAM KEY: Femoral tunnel depth depends on fixation method - this is critical decision point. For INTERFERENCE SCREW use blind tunnel 25-30mm depth (do NOT penetrate far cortex or screw will not engage). For SUSPENSORY FIXATION (EndoButton, TightRope) MUST drill completely through lateral femoral cortex - measure condyle thickness first with depth markings on guide pin (usually 35-40mm), then ream 5mm deeper to ensure complete cortex penetration. Many surgeons now use hybrid fixation (suspensory femoral, interference tibial) as this preserves femoral bone stock for potential revision. The tunnel aperture should be perfectly ROUND - oval tunnels indicate malposition (guide slipped during reaming) or reamer wobble (inadequate guide pin fixation). Bone quality in distal femur is excellent - hard metaphyseal bone provides strong fixation. Check for cystic changes from chronic ACL deficiency - if present, may need longer tunnel or supplemental fixation. The tunnel position is verified by 'anatomic box' bounded by: Resident's Ridge anteriorly, deep cartilage superiorly, over-the-top position posteriorly, Blumensaat's line (roof) on lateral X-ray. Tunnel should be in posterior half of this box. Some surgeons routinely take intraoperative fluoroscopic lateral X-ray to document femoral tunnel position (should be in posterior half of Blumensaat's line). - Drilling too deep through far cortex for interference screw fixation - screw will not engage bone - Tunnel too shallow (less than 25mm) - inadequate fixation length, screw backs out - Eccentric reaming or guide pin slippage - oval tunnel, malposition, poor fixation - Posterior wall fracture during reaming - loss of fixation, need for revision or supplemental fixation - Not measuring depth accurately - either too short or breakthrough when not intended ### Step 9: Graft passage through tunnels Graft passage through tunnels: Retrieve shuttle suture previously passed through tibial tunnel, bringing it out anteromedial portal. Attach graft sutures (from TIBIAL bone block end - this end passes first) to shuttle suture using secure knot or suture-grasping technique. Begin graft passage by pulling shuttle suture out through tibial tunnel while feeding graft into anteromedial portal - the tibial bone block passes first through joint, then up through tibial tunnel (retrograde direction). Assistant pushes graft gently from inside joint using arthroscopic nerve hook or grasper while surgeon pulls sutures from tibial tunnel exit. The graft should pass smoothly without excessive force. Watch arthroscopically throughout passage to ensure: 1) no twisting (verify orientation marks if used), 2) smooth passage without catching on tunnel edges, 3) femoral bone block enters femoral tunnel correctly. As tibial bone block exits anterior tibia and tendon graft traverses joint, begin advancing femoral bone block into femoral tunnel. Use nerve hook or switching stick to guide femoral bone block into tunnel entrance while pulling from tibial side provides tension. The femoral bone block should seat completely within femoral tunnel with gentle sustained traction - if excessive force required, STOP and troubleshoot. Once femoral bone block is fully seated (completely within tunnel, no toggle), confirm position with probe arthroscopically - block should not be visible in joint. Ensure graft is not twisted by inspecting fiber orientation (should run in parallel lines without spiral pattern). The graft should lie in anatomic position spanning from femoral tunnel to tibial tunnel without impingement on PCL, intercondylar roof, or medial wall. **Technical Tip**: EXAM KEY: Graft passage is critical step - NEVER force the graft as this damages graft fibers reducing tensile strength by 30-50%. If passage is difficult (resistance or will not advance), systematically check: 1) Sharp tunnel edges (chamfer more), 2) Tunnel too small (ream 0.5mm larger), 3) Bone block too large or irregular (trim or re-shape), 4) Debris in tunnel (irrigate and curette), or 5) Trajectory misalignment (reposition or use different technique). The graft MUST NOT be twisted during passage - twisting alters biomechanics, creates stress concentrations, and reduces strength. Some surgeons mark graft with sterile marking pen preoperatively to verify orientation. Pull with gentle steady tension - jerking motions damage graft fibers. Watch arthroscopically throughout to see exact graft position during passage. The femoral bone block must seat COMPLETELY in tunnel - partial seating leads to graft elongation ('bungee effect') and failure. Test seating by gentle tugging on tibial sutures - femoral block should not toggle or move. If block will not seat fully, likely causes: tunnel too short (ream deeper), bone block too long (trim), or tunnel debris (clear). Do not proceed with fixation until perfect femoral bone block seating confirmed. - Forcing graft with excessive tension - fiber damage reducing strength 30-50%, predisposes to failure - Graft twisting during passage - altered biomechanics, stress concentration, early failure - Incomplete femoral bone block seating - graft elongation, loss of fixation, inevitable failure - Graft abrasion on sharp tunnel edges - 'windshield wiper' lesion, progressive failure - Bone block fracture during passage - loss of fixation, need for revision or supplemental fixation ### Step 10: Femoral fixation - interference screw technique Femoral fixation - interference screw technique: With femoral bone block confirmed fully seated in tunnel by probe testing, prepare for interference screw fixation of femoral side. Size interference screw appropriately: diameter should be 1mm LARGER than tunnel diameter (9mm tunnel requires 10mm screw, 10mm tunnel requires 11mm screw) to achieve compression; length should equal bone block length plus 5-10mm (typically 25-30mm total for 20-25mm bone block). Choose screw material based on patient factors and surgeon preference: metal (titanium) provides strongest fixation (700N ultimate load) and least risk of divergence but causes significant MRI artifact limiting postoperative imaging; bioabsorbable (PLLA, PLGA) avoids MRI artifact and eventually resorbs but weaker fixation (500-600N), risk of inflammatory foreign body reaction (5-10%), tunnel widening, and incomplete resorption with cyst formation (5%). Position interference screw guide wire ANTERIOR to graft (between graft and anterior tunnel wall) - this 'divergent' position compresses graft against posterior tunnel wall providing strong fixation. NEVER place screw posterior to graft ('parallel' position) as this pushes graft forward against anterior tunnel edge causing abrasion and failure. Insert screw driver with interference screw mounted over guide wire, advancing through femoral tunnel. Watch arthroscopically while advancing screw - should see bone block compressing posteriorly against tunnel wall. Advance screw with firm steady pressure using power driver on low torque setting. The screw should engage bone and compress bone block - if screw advances with minimal resistance, may be diverging outside tunnel into soft tissue. Stop if screw advances more than expected length (suggests divergence). Continue until screw head is flush with articular surface of tunnel aperture or resistance increases significantly indicating full seating. Remove guide wire. Test fixation by pulling gently on tibial sutures - femoral block should not toggle or move. **Technical Tip**: EXAM KEY: Fix FEMORAL side FIRST before tibial side (opposite sequence from hamstring reconstruction) - this allows proper graft tensioning at tibial side. Screw diameter MUST be 1mm LARGER than tunnel for adequate compression - same size or smaller will not compress and bone block will toggle and fail. The screw MUST be placed ANTERIOR to graft (divergent position) compressing graft posteriorly - this is biomechanically superior (700N vs 400N parallel position) and prevents graft abrasion. Placing screw posterior or parallel to graft damages graft fibers during insertion and creates ongoing abrasion point leading to failure. Metal (titanium) screws are biomechanically superior to bioabsorbable (700N vs 500N ultimate load, lower divergence rate 5% vs 15%) but cause substantial MRI artifact making postoperative imaging difficult (obscures graft evaluation). Bioabsorbable screws avoid artifact but risk inflammatory reaction (5-10% develop sterile effusion, pain), tunnel cyst formation (5%), and incomplete resorption. Watch for screw DIVERGENCE during insertion - if screw advances with minimal resistance or advances more than expected length, it's tracking outside tunnel in soft tissue rather than compressing bone - must remove and redirect. Ensure screw engages BONE not just soft tissue - need bone-to-bone compression for healing and stable fixation. Stop advancing when screw head flush with tunnel aperture - over-advancement buries screw causing difficulty if removal needed. - Screw divergence outside tunnel - loss of fixation, graft toggle and failure (occurs in 10-15% with bioabsorbable) - Screw placed through or posterior to graft - fiber damage, ongoing abrasion, eventual failure - Screw too long - penetrates lateral femoral cortex causing skin irritation, hardware prominence - Screw too short - inadequate compression, bone block not fully secured - Stripping screw threads or splitting bone block - over-torquing, bone quality poor, need supplemental fixation ### Step 11: Graft tensioning and preparation for tibial fixation Graft tensioning and preparation for tibial fixation: With femoral side securely fixed, begin graft tensioning protocol. Cycle knee through full range of motion 20-25 times while applying gentle manual tension on tibial bone block sutures (pull with 15-20 pounds or 70-90N force). During cycling, watch graft arthroscopically - it should appear taut throughout range of motion without going slack (indicates isometric position), and without impingement on intercondylar roof in extension, PCL posteriorly, or medial wall (indicates malposition requiring correction). This cycling serves multiple purposes: eliminates graft creep (initial tensioning stretches graft 3-4mm), allows graft to settle into optimal isometric position, identifies any impingement requiring notchplasty. If impingement is visible during cycling, perform additional notchplasty before final fixation - remove bone from anterior roof if roof impingement, or widen notch laterally if wall impingement. After cycling, position knee in 10-20 degrees of flexion (NOT full extension which over-constrains graft causing loss of flexion) - use goniometer or estimate by placing two fingerbreadths under heel. Apply POSTERIOR DRAWER force to tibia while maintaining graft tension - push posterior drawer manually while tensioning graft distally. This posterior drawer prevents over-tensioning by reducing tibia relative to femur. The graft should be 'just tight' - firm tension but not rigid like guitar string. Hold this exact position (10-20 degrees flexion, posterior drawer applied, appropriate graft tension) while assistant prepares tibial interference screw and maintains position. Surgeon maintains tension on graft sutures with consistent force until tibial fixation complete. **Technical Tip**: EXAM KEY: Graft tensioning is CRITICAL for outcomes - this step determines final knee kinematics and stability. Under-tensioning causes residual laxity, giving way, and patient dissatisfaction. Over-tensioning causes loss of flexion, arthrofibrosis, and potential graft failure. The 'goldilocks' position is 10-20 degrees flexion with POSTERIOR DRAWER applied - this prevents over-constraint. NEVER fix in full extension (0 degrees) as this over-tensions graft causing loss of flexion and arthrofibrosis in 15-20% of cases. The posterior drawer force during tensioning is critical - reduces tibia posteriorly preventing over-tension. Cycle knee 20-25 times before final fixation - initial tensioning stretches graft up to 3-4mm (creep) which would lead to laxity if not eliminated. Some surgeons use mechanical tensioning devices (25 pounds or 110N), others use manual tension - both effective if technique consistent. The key is CONSISTENCY - same tension, same knee position, same technique every case. Graft should appear 'just tight' arthroscopically - firm throughout ROM but not maximally tensioned. Check for impingement systematically: extension (roof), mid-flexion (Resident's ridge), deep flexion (PCL), lateral wall throughout. If ANY impingement visible, address with notchplasty BEFORE final fixation - impingement causes graft abrasion and failure in 10-15% of cases. Many surgeons verify tension using manual Lachman - should feel solid endpoint with minimal translation (less than 3mm). - Fixing graft in full extension (0 degrees) - over-constraint, loss of flexion, arthrofibrosis - Under-tensioning - residual laxity (grade 2-3 Lachman), giving way, poor outcome - Not applying posterior drawer during tensioning - over-tension, loss of flexion - Missing graft impingement on cycling - progressive abrasion and failure - Inconsistent tensioning between cases - unpredictable outcomes ### Step 12: Tibial fixation - interference screw technique Tibial fixation - interference screw technique: While assistant maintains exact knee position (10-20 degrees flexion with posterior drawer applied) and graft tension on sutures, surgeon prepares tibial interference screw. Size tibial screw: diameter 1mm larger than tunnel (10mm tunnel requires 11mm screw), length 25-30mm to engage tibial bone block fully (20-25mm block plus 5mm extra). Choose metal versus bioabsorbable based on same criteria as femoral side (metal stronger and less divergence risk, bioabsorbable avoids MRI artifact). Position screw guide wire ANTERIOR to graft (between graft and anterior tibial tunnel wall - divergent position) - identical technique to femoral side. Insert interference screw over guide wire, advancing with power driver on low torque setting. Assistant maintains constant graft tension throughout screw insertion - critical to prevent tension loss. Watch for screw divergence (minimal resistance or excessive advancement). The screw should compress tibial bone block against posterior tunnel wall. Advance screw until head is flush with anterior tibial cortex or resistance increases significantly indicating full seating. Do not over-tighten as this can strip threads in softer tibial metaphyseal bone or split bone block. Remove guide wire. Cut graft sutures at tibial tunnel exit (some surgeons tie sutures over screw head or bone bridge for supplemental fixation). Perform final stability testing: manual Lachman test should demonstrate solid endpoint with minimal translation (0-3mm, grade 0-1), anterior drawer should be firm, pivot shift should be negative (grade 0). Cycle knee through full ROM - should be smooth without catching, mechanical block, or pain. Measure ROM with goniometer: extension should be 0 degrees (full), flexion should reach 130-140 degrees (normal). If extension loss over 5 degrees or flexion less than 120 degrees, graft is over-tensioned or impinging - requires troubleshooting before proceeding. **Technical Tip**: EXAM KEY: Tibial fixation technique is identical to femoral - screw MUST be ANTERIOR to graft (divergent position), 1mm LARGER than tunnel diameter for compression. The critical error is releasing graft tension before screw is fully seated - assistant MUST maintain exact tension throughout entire screw insertion. Loss of tension even briefly causes permanent graft elongation and laxity. Some surgeons use supplemental fixation for high-demand athletes or revision cases: screw plus suture tie-down over bone bridge or screw post, or screw with spiked washer/sheath to distribute load and prevent bone block pull-through. Tibial bone is softer metaphyseal bone (vs hard distal femur) so screw divergence rate higher (15-20% vs 5-10% femoral) and stripping threads more common if over-torqued - use gentle technique and stop when resistance increases. Test stability immediately after fixation while still sterile - Lachman should improve dramatically from pre-op (grade 3 to grade 0-1). Gentle resistance with solid endpoint is expected and normal. If soft endpoint persists (grade 2-3 laxity), graft is malpositioned, under-tensioned, or fixation inadequate - must troubleshoot cause. Post-fixation ROM MUST be full - extension 0 degrees (inability to extend suggests over-tensioning requiring revision), flexion to 130 degrees minimum (inability to flex suggests impingement or patella infera). Do NOT accept 5-10 degree extension loss thinking it will resolve with therapy - it will not and leads to arthrofibrosis disaster. If ROM limited, must revise tensioning or tunnel position before closing. - Loss of graft tension during screw insertion - permanent elongation and laxity - Screw divergence in soft tibial metaphyseal bone - inadequate fixation, failure risk - Over-tightening screw - stripping threads, bone block fracture - Screw through graft - fiber damage and progressive failure - Accepting limited ROM after fixation - arthrofibrosis or impingement not addressed ### Step 13: Final graft assessment and verification Final graft assessment and verification: Perform systematic final arthroscopic assessment of graft position, tension, and kinematics. View graft from both anteromedial and anterolateral portals sequentially. With knee in extension (0 degrees), graft should lie in center of intercondylar notch without touching roof (Blumensaat's line on lateral X-ray shows graft parallel to roof with 2-3mm clearance) or lateral wall. With knee in 90 degrees flexion, graft should be visible, taut, and appropriately tensioned. Cycle knee slowly through full ROM (0-135 degrees) while watching graft arthroscopically - graft should remain ISOMETRIC (constant tension without going slack or becoming overly tight) throughout range. Test systematically for impingement at critical points: full extension (roof impingement - graft should clear roof by 2-3mm), 30-45 degrees flexion (Resident's Ridge impingement), 90 degrees flexion (graft should be visible and taut), deep flexion 120+ degrees (check PCL clearance). If ANY impingement present, perform additional notchplasty immediately - remove bone from anterior roof if roof impingement (most common), widen lateral notch if wall impingement, remove anterior prominence (cyclops remnant) if mid-flexion catching. Test graft stability manually with arthroscopic probe - should be firm without toggle, excessive motion, or bouncing (indicates fixation failure). Remove arthroscope and perform final clinical examination: Lachman test should be grade 0-1 (0-3mm translation with solid endpoint), anterior drawer should be firm grade 0-1, pivot shift should be negative (grade 0 - smooth glide without clunk or subluxation). Measure final ROM with goniometer: extension MUST be 0 degrees (any loss over 5 degrees requires intervention), flexion should reach minimum 120 degrees (preferably 130-135 degrees matching normal). If extension loss present, causes include: over-tensioning, roof impingement, cyclops lesion forming, or anterior arthrofibrosis - requires immediate arthroscopic re-evaluation and correction before closing. If flexion limited (less than 120 degrees), causes include: over-tensioning, patella baja, adhesions - requires assessment and usually graft re-tensioning. **Technical Tip**: EXAM KEY: Final graft verification is MANDATORY step - multiple studies show tunnel malposition occurs in 20-30% of cases and is associated with early failure if not corrected. The graft should demonstrate ISOMETRIC behavior (constant tension through ROM) - if graft goes slack in any position it's malpositioned (too anterior if slack in flexion, too posterior if slack in extension). Impingement is common cause of failure (10-15%) - check systematically at extension (roof), mid-flexion (Resident's Ridge), deep flexion (PCL). Use probe to feel for impingement - can be subtle visually but palpable with probe. The graft should NEVER touch PCL at any point in ROM - if contact present, tibial tunnel is too posterior requiring revision. ROM MUST be full and symmetric to contralateral knee - loss of extension over 5 degrees is DISASTER leading to patella baja and arthrofibrosis (affects 20% of outcomes if present). Do not accept limited extension thinking therapy will restore it - it will NOT without intervention. If extension limited: 1) Re-examine for impingement and perform additional notchplasty, 2) Check graft tension (may need to release tibial fixation and re-tension at less tension), 3) Rule out cyclops lesion (anterior nodule of scar tissue), or 4) Perform anterior interval release if adhesions. Address immediately before closing - much harder to correct later. Many surgeons routinely obtain intraoperative fluoroscopic images documenting final tunnel positions for medicolegal purposes and future reference if failure occurs - lateral view shows Blumensaat's line with femoral tunnel position (should be posterior half), tibial tunnel angle (50-60 degrees), and graft position (parallel to roof with clearance). AP view shows tibial tunnel position relative to spines and PCL. - Missing impingement signs - progressive graft abrasion and failure within 2-5 years - Accepting extension loss (over 5 degrees) - inevitable arthrofibrosis, patella baja, poor outcome - Non-isometric graft behavior not recognized - malposition causing failure - Graft-PCL contact throughout ROM - tibial tunnel malposition requiring revision - Inadequate clinical stability testing - fixation failure not recognized until postoperative period ### Step 14: Patellar tendon donor site repair and closure Patellar tendon donor site repair and closure: Inspect patellar tendon harvest site and bone defects carefully. Close patellar tendon harvest defect to minimize adhesions and reduce anterior knee pain risk. Technique varies by surgeon preference: some approximate remaining tendon edges side-to-side with interrupted absorbable sutures (#1 or #2 Vicryl) to narrow defect and provide smoother surface; others leave defect open citing concern that closure increases tension on repair increasing rupture risk - neither approach proven superior by evidence. If closing tendon defect, use interrupted figure-of-eight sutures with minimal tension, approximating edges without strangulating tissue. Most important layer is paratenon/peritenon repair - close this layer meticulously over tendon defect using running absorbable suture (2-0 or 3-0 Vicryl) to provide smooth gliding surface and reduce adhesions to overlying subcutaneous tissue. Ensure infrapatellar fat pad is positioned properly anterior to patellar tendon (not trapped in tendon defect which causes pain, restricted motion, and patella baja). Irrigate wound copiously to remove debris and bone fragments. Check hemostasis carefully - anterior knee is very vascular and hematoma increases adhesion formation. Close subcutaneous tissue in layers using absorbable sutures (2-0 and 3-0 Vicryl) with minimal tension. Close skin with running subcuticular absorbable suture (4-0 Monocryl) or skin staples based on preference. Apply sterile dressing with moderate compression using ABD pads and Kerlix wrap. Do not apply excessive compression as this risks compartment syndrome. Place knee in hinged brace locked in extension (0 degrees) or apply well-padded posterior splint from ankle to upper thigh for comfort and graft protection during sleep and transfers. **Technical Tip**: EXAM KEY: Donor site closure technique affects anterior knee pain rates (most common long-term complaint 10-30%) - careful peritenon/paratenon repair reduces adhesions and improves outcomes. Some surgeons close tendon defect side-to-side with interrupted sutures to narrow gap, others leave open - Level 1 evidence shows NO significant difference in outcomes or complications (rupture rate 0.5-1% either technique). The CRITICAL layer is paratenon which provides smooth gliding surface - must close this layer meticulously to prevent adhesions to subcutaneous fat and skin. Technique: run 3-0 Vicryl in continuous fashion approximating paratenon edges over defect creating smooth covering. Avoid trapping infrapatellar fat pad in tendon defect - this causes significant pain, restricted motion, and contributes to patella baja formation. Fat pad should be positioned anterior to tendon in normal anatomic position. Don't over-tighten tendon repair as this increases tension on remaining tendon fibers increasing rupture risk - sutures should approximate edges without strangulation. The bone defects at patella (inferior pole) and tibia (tubercle) will fill with fibrous tissue and eventually ossify over 6-12 months - do not attempt to fill or close these defects. Postoperative patellar fracture risk is highest at 6 weeks to 3 months when stress risers are maximal before remodeling complete - protect patient during this period with activity restrictions and brace. Stress fracture through patellar harvest site occurs in 0.3-1% (100-fold higher than background patellar fracture rate) - counsel patients about symptoms (anterior knee pain, inability to straight leg raise) and need for urgent evaluation if develop. - Fat pad entrapment in tendon defect - severe anterior knee pain, restricted motion, patella baja - Over-tight tendon repair - increased tension on residual tendon, rupture risk - Inadequate paratenon closure - adhesions to skin/subcutaneous tissue, chronic pain - Poor hemostasis - hematoma formation increasing adhesions and infection risk - Excessive compression dressing - compartment syndrome (rare but devastating) ### Step 15: Portal closure and dressing application Portal closure and dressing application: Close arthroscopic portals with single interrupted sutures (typically 3-0 or 4-0 nylon or absorbable monofilament). Ensure hemostasis before closure by irrigating and inspecting for bleeding vessels - cauterize if needed. Inject local anesthetic (20-30cc of 0.25% bupivacaine or ropivacaine) intra-articularly through arthroscopic portal for postoperative pain control - provides excellent analgesia for first 12-24 hours. Avoid injecting directly into graft as local anesthetics have chondrotoxic effects - inject into suprapatellar pouch and dependent recesses distant from graft. Apply sterile dressing with moderate compression using ABD pads and soft roll (Kerlix). Apply hinged knee brace locked in extension (0 degrees) for comfort and graft protection - patient will unlock brace during physical therapy sessions but lock for ambulation and sleep first 1-2 weeks. Alternatively, apply well-padded posterior plaster or fiberglass splint from ankle to upper thigh maintaining knee in full extension (some surgeons prefer splint for better protection first 48-72 hours). Elevate leg on pillows maintaining ankle above heart level to reduce swelling. Apply ice or cryotherapy device (continuous cold flow machines superior to ice packs for pain and swelling control). Deflate and remove tourniquet after dressing applied. Document procedure details comprehensively in operative note including: graft source and dimensions, tunnel positions and sizes, fixation methods and hardware used, ROM achieved, stability testing results, any complications or technical issues, estimated blood loss, tourniquet time. Many surgeons routinely obtain immediate postoperative radiographs (AP and lateral knee) to document final tunnel positions for future reference - lateral view most useful showing Blumensaat's line, femoral tunnel position (should be posterior half of line), tibial tunnel angle (50-60 degrees from plateau), and graft trajectory. Mark radiographs with measurements for medicolegal documentation. **Technical Tip**: EXAM KEY: Intra-articular local anesthetic (bupivacaine 0.25% or ropivacaine 0.2%, volume 20-30cc) provides excellent postoperative pain control for first 12-24 hours - reduces narcotic requirements by 50-70% and improves early rehabilitation compliance. Long-acting agents (bupivacaine, ropivacaine) superior to short-acting (lidocaine). Avoid injecting directly into graft or fixation sites as local anesthetics are chondrotoxic at high concentrations - inject into suprapatellar pouch distant from graft. Extension brace locked at 0 degrees for first 1-2 weeks protects graft during sleep and ambulation when patient may be unstable or unaware (prevents inadvertent pivoting or giving way causing graft failure) but MUST allow ROM exercises during supervised therapy sessions to prevent stiffness. Some surgeons use posterior splint first 48-72 hours for better immobilization, then transition to hinged brace. Compression dressing reduces hemarthrosis and swelling but avoid excessive compression (compartment syndrome risk, though rare). Cryotherapy/continuous cold flow machines (Polar Care, Game Ready) more effective than ice packs alone for pain and swelling control - reduce pain scores by 30-40% and swelling by 20-30%. Many surgeons routinely obtain postoperative radiographs to document tunnel positions for several reasons: 1) Medicolegal documentation of technique, 2) Baseline for comparison if failure occurs, 3) Quality control and learning (can measure tunnel positions and correlate with outcomes). Lateral view most important - shows Blumensaat's line (intercondylar roof), femoral tunnel position should be in posterior 50% of line (anterior position indicates vertical non-anatomic tunnel), tibial tunnel angle should be 50-60 degrees from plateau (steeper or shallower indicates malposition). Can measure tunnel positions precisely using grid overlay or digital measurement tools. Document comprehensively in operative note - this is medicolegal protection if complications occur and helpful for future surgeons if revision needed. - Injecting local anesthetic directly into graft - chondrotoxicity causing graft damage - Inadequate hemostasis before closure - hemarthrosis (stiff knee, increased pain, adhesions) - Overly tight compression dressing - compartment syndrome (very rare, less than 0.1%) - Brace unlocked during unsupervised ambulation - graft injury from giving way episode - Incomplete operative documentation - medicolegal vulnerability, difficulty with revision planning ## Immediate Postoperative Period (0-24 hours) **Pain Management**: Multimodal analgesia including intra-articular local anesthetic (bupivacaine), oral NSAIDs (if no contraindication - avoid first 6 weeks if concerned about bone healing per some literature, though controversial), acetaminophen, opioids as needed for breakthrough pain (minimize use - typically 1-3 days only). Regional blocks (femoral nerve block, adductor canal block) provide excellent pain control but may delay quadriceps activation. **Cryotherapy**: Ice or continuous cold flow machine for 20-30 minutes every 2-3 hours while awake. Reduces pain, swelling, narcotic requirements. **Elevation**: Leg elevated on pillows maintaining ankle above heart level to minimize swelling. **VTE Prophylaxis**: Mechanical compression (TED hose, sequential compression devices) for all patients. Chemical prophylaxis (aspirin 325mg daily or LMWH) for high-risk patients (BMI over 40, prior VTE, thrombophilia, prolonged immobility). Low overall VTE risk (0.3-0.8%) with ACL reconstruction. **Weight-Bearing**: Weight-bearing as tolerated with crutches for comfort and safety (typically 1-2 weeks). Full weight-bearing when gait normalized and quadriceps control adequate. **Brace**: Hinged brace locked in extension for ambulation and sleep first 1-2 weeks, unlocked 0-90 degrees for exercises. ## Early Rehabilitation Phase (Weeks 1-6) Focus on regaining full ROM (especially extension), quadriceps activation, minimizing swelling, normalizing gait. **ROM**: Immediate emphasis on achieving full extension (0 degrees) - heel props, prone hangs, extension stretches multiple times daily. Flexion 0-90 degrees week 1, progressing to full ROM (0-135 degrees) by week 4-6. Patellar mobilization all directions to prevent adhesions. **Strengthening**: Quadriceps sets, straight leg raises (when quad control present - typically 3-7 days), ankle pumps, multi-angle isometrics. Avoid hamstring exercises first 6 weeks (protective for healing ACL). Closed-chain exercises (wall sits, mini-squats 0-45 degrees) starting week 2-3. **Proprioception**: Single-leg balance (progress from bilateral to unilateral, eyes open to eyes closed, stable to unstable surface). **Cardiovascular**: Stationary bike when 90-110 degrees flexion achieved (typically week 2-3), starting with no resistance. Pool walking if available. **Criteria to Progress**: Full passive ROM (0-130 degrees), minimal effusion, quad strength 60-70% contralateral, normal gait without assistive devices. ## Intermediate Rehabilitation (Weeks 6-12) Progressive strengthening, beginning functional training, return to activities of daily living. **Strengthening**: Leg press (90-0 degrees full ROM), step-ups/downs (progressive height), lunges, single-leg squats, hamstring curls (now permitted after 6 weeks), core strengthening, hip abductor/adductor strengthening. **Cardiovascular**: Bike resistance progressing, elliptical trainer, swimming (avoid breaststroke kick first 3 months). **Proprioception**: Advanced balance drills, perturbation training, sport-specific movements at slow speed. ## Advanced Rehabilitation (Months 3-6) Return to running, plyometrics, agility training. **Running**: Initiated when quad strength 80% or more of contralateral (typically month 3-4). Start with straight-line treadmill jogging, progress to outdoor running, add intervals and hills gradually. **Plyometrics**: Jumping, hopping, bounding progressions. Start double-leg, progress to single-leg. **Agility**: Cutting, pivoting, lateral movements in controlled environment. Progress speed and complexity gradually. **Sport-Specific**: Position-specific drills, skills training. **Criteria to Progress**: Quad/hamstring strength 85% or more contralateral, hop testing symmetry over 90%, confidence with agility movements. ## Return to Sport (Months 9-12) Minimum 9 months, ideally 12 months or more before full return to competition. **Clearance Criteria (ALL must be met)**: - Time: Minimum 9 months (return before 9 months doubles re-rupture risk from 5% to 10%) - Strength: Quadriceps and hamstring isokinetic testing 90% or more of contralateral - Hop testing: Single-hop, triple-hop, crossover-hop, timed-hop all within 90% of contralateral - Functional testing: ACL-RSI psychological readiness score over 60 - Clinical: Grade 0-1 Lachman, negative pivot shift, full ROM - Surgeon clearance **Graduated Return**: Begin with practice participation (no contact), progress to full practice, then limited competition, finally unrestricted play. ## References 1. **Gorschewsky O, Klakow A, Pütz A, Mahn H, Neumann W.** Clinical comparison of the Tutoplast allograft and autologous patellar tendon (bone-patellar tendon-bone) for the reconstruction of the anterior cruciate ligament: 2- and 6-year results. *Am J Sports Med.* 2005;33(8):1202-1209. doi:10.1177/0363546504271510 2. **Pinczewski LA, Lyman J, Salmon LJ, Russell VJ, Roe J, Linklater J.** A 10-year comparison of anterior cruciate ligament reconstructions with hamstring tendon and patellar tendon autograft: a controlled, prospective trial. *Am J Sports Med.* 2007;35(4):564-574. doi:10.1177/0363546506296042 3. **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 4. **Mascarenhas R, MacDonald PB.** Anterior cruciate ligament reconstruction: a look at prosthetics--past, present and possible future. *McGill J Med.* 2008;11(1):29-37. 5. **Barrett AM, Craft JA, Replogle WH, Hydrick JM, Barrett GR.** Anterior cruciate ligament graft failure: a comparison of graft type based on age and Tegner activity level. *Am J Sports Med.* 2011;39(10):2194-2198. doi:10.1177/0363546511415655 6. **Rothrauff BB, Karlsson J, Musahl V, Irrgang JJ, Fu FH, Samuelsson K.** Anatomic ACL reconstruction reduces risk of post-traumatic osteoarthritis: a systematic review and meta-analysis. *Knee Surg Sports Traumatol Arthrosc.* 2020;28(4):1072-1084. doi:10.1007/s00167-019-05665-2 7. **Lubowitz JH, Schwartzberg R, Smith P.** Randomized controlled trial comparing all-inside anterior cruciate ligament reconstruction technique with anterior cruciate ligament reconstruction with a full tibial tunnel. *Arthroscopy.* 2013;29(7):1195-1200. doi:10.1016/j.arthro.2013.04.009 8. **Mayr R, Heinrichs CH, Eichinger M, Smekal V, Schmoelz W, Attal R.** Biomechanical comparison of 2 anterior cruciate ligament graft preparation techniques for tibial fixation: adjustable-length loop cortical button or interference screw. *Am J Sports Med.* 2015;43(6):1380-1385. doi:10.1177/0363546515574062 9. **Noyes FR, Barber-Westin SD.** Anterior cruciate ligament revision reconstruction: results using a quadriceps tendon-patellar bone autograft. *Am J Sports Med.* 2006;34(4):553-564. doi:10.1177/0363546505281805 10. **Gokeler A, Welling W, Zaffagnini S, Seil R, Padua D.** Development of a test battery to enhance safe return to sports after anterior cruciate ligament reconstruction. *Knee Surg Sports Traumatol Arthrosc.* 2017;25(1):192-199. doi:10.1007/s00167-016-4246-3

ACL Reconstruction with Bone-Patellar Tendon-Bone Autograft

ACL Reconstruction with Bone-Patellar Tendon-Bone Autograft