High Yield Overview

ACL RECONSTRUCTION - BONE-PATELLAR TENDON-BONE (BTB) AUTOGRAFT

Arthroscopic via anterolateral viewing and anteromedial working portals. Central midline incision over patellar tendon for BTB harvest (can use small medial parapatellar incision alternatively). | intermediate

Critical Danger Structures

Infrapatellar Branch of Saphenous Nerve

Location: Crosses medial aspect of patellar tendon obliquely 1-2cm below inferior pole of patella, runs superficially in subcutaneous tissue

Protection: Use vertical midline incision (not medial parapatellar which transects nerve). Accept universal numbness of anterolateral knee as unavoidable with any approach

Patellar Blood Supply - Extraosseous Anastomotic Ring

Location: Vascular ring formed by superior and inferior geniculate arteries surrounds patella in periosteum and attached capsular tissue

Protection: Minimize periosteal stripping during bone plug harvest - use saw for precise cuts. Maintain paratenon coverage. Excessive stripping risks patellar AVN (rare but reported)

Lateral Patellar Tendon Remnants (Medial and Lateral Strips)

Location: Remaining medial and lateral portions of patellar tendon after central third harvest - must be minimum 5mm width each side (ideally 7-8mm)

Protection: Precisely measure and mark central third (10mm width maximum). Use ruler to ensure adequate remnants. Inadequate remnants increase rupture risk 5-10 fold (baseline 0.5-1%)

Tibial Tubercle Apophysis

Location: Secondary ossification center at tibial tuberosity - fuses to proximal tibia at age 15-17 years in males, 13-15 years in females

Protection: In adolescents, palpate and visualize apophyseal line on fluoroscopy/radiographs. Harvest tibial bone plug proximal to apophysis avoiding cartilaginous junction to prevent avulsion injury

Posterior Cruciate Ligament (PCL)

Location: Runs from medial femoral condyle to posterior tibial plateau - positioned immediately posterior to ACL footprint and intercondylar notch

Protection: During notch debridement, stay anterior and preserve posterior ACL remnant fibers as barrier. During tibial tunnel drilling, avoid posterior malposition >7mm behind anterior tibial spine which risks PCL perforation

Positioning and Preparation

Patient Position: Supine with commercial leg holder (or lateral thigh post) allowing full ROM. Tourniquet on thigh (optional - I prefer not to use routinely). Ensure full passive extension to 0° and flexion >120°. Hip flexed 30-45°. Contralateral leg in stirrup or abducted on leg rest.

Surgical Approach: Arthroscopic via anterolateral viewing and anteromedial working portals. Central midline incision over patellar tendon for BTB harvest (can use small medial parapatellar incision alternatively).

Incision: Portal incisions: 5mm stab incisions at joint line - anterolateral 1cm lateral to patellar tendon, anteromedial adjacent to medial patellar tendon border. BTB harvest: 6-8cm vertical midline incision from inferior pole of patella to tibial tubercle, centered over patellar tendon.

Mnemonic

HARVESTHARVEST - BTB Graft Procurement Checklist

Mnemonic

TUNNELTUNNEL - Anatomic Tunnel Positioning Principles

BTB Graft Classification Systems

Graft Harvest Techniques

Patellar Tendon Width Classification

Central Third (Standard): 10mm width from central patellar tendon
Narrowed Graft: 8mm width for smaller patients or wider remnant preservation
Medial Third: Alternative harvest from medial portion (preserves lateral for future surgery)

Bone Plug Harvest Methods

Oscillating Saw Technique: Precise cuts, minimal fracture risk, preferred method
Osteotome Technique: Risk of fracture propagation, outdated
Trephine Technique: Cylindrical plugs, risk of plug divergence

Tunnel Drilling Approaches

Femoral Tunnel Techniques

Transtibial: Through tibial tunnel at 90° flexion - results in non-anatomic high anterior tunnel position
Trans-Anteromedial Portal (Preferred): Independent drilling at 110-120° flexion - achieves anatomic footprint position
Outside-In: Through lateral femoral cortex - technically demanding, risk of divergence
All-Inside: Suspensory fixation, no cortical breach - allows bone plug retention but loses bone-to-bone healing

Tibial Tunnel Techniques

Standard Transtibial: 55° angle via anteromedial approach - standard technique
Two-Incision: Separate anterior incision for guide placement - outdated
All-Inside: Retrograde drilling - preserves tibial cortex for future revision

Fixation Method Classification

Femoral Fixation Options

Interference Screw (Preferred for BTB): Metal or bioabsorbable, 7-9mm diameter, highest pullout strength >1000N
Cross-Pin Fixation: TransFix or RigidFix devices - more complex, no clear advantage
Cortical Button with Post: RetroButton or Endobutton - for suspensory backup fixation
Hybrid Fixation: Interference screw plus cortical backup - belt-and-suspenders approach

Tibial Fixation Options

Interference Screw (Preferred): 7-9mm diameter, 20-25mm length, placed parallel to bone plug
Post and Washer: Screw with spiked washer over cortical surface - backup fixation
Staple Fixation: Historical method, outdated due to loosening

Evidence-Based Graft Selection

BTB vs Hamstring Autograft - Meta-Analysis Data

Failure Rates (Equivalent)

BTB: 5-10% failure rate at 5-10 years
Hamstring: 5-10% failure rate at 5-10 years
No significant difference in multiple meta-analyses (>20 studies, >5000 patients)

Stability Outcomes (Equivalent)

Lachman test positive: BTB 5-10%, Hamstring 5-10%
Pivot shift positive: BTB 5-8%, Hamstring 5-10%
Side-to-side difference >3mm: BTB 8-12%, Hamstring 10-15%
Both restore stability equally well

Return to Sport (Slight BTB Advantage)

BTB: 80-85% return to pre-injury level at 9-12 months
Hamstring: 75-80% return to pre-injury level at 9-12 months
BTB may allow 4-6 weeks earlier RTS due to faster bone healing (controversial)

Donor Site Morbidity (BTB Disadvantage)

Anterior knee pain: BTB 20-30%, Hamstring 10-15% (significant difference)
Kneeling pain: BTB 30-40%, Hamstring 10-15% (significant difference)
Subjective knee scores: Slightly favor hamstring in some studies

Patient-Specific Selection Criteria

Prefer BTB Autograft

High-demand collision athletes (rugby, AFL, NFL, hockey)
Military, law enforcement, firefighters
Revision ACL reconstruction (bone-to-bone healing advantage)
Multi-ligamentous knee injury requiring strong fixation
Patient preference for "gold standard" with longest data
Concurrent bony procedures (high tibial osteotomy, meniscal transplant)

Prefer Hamstring Autograft

Occupations requiring kneeling (carpet layers, plumbers, tilers)
Patients prioritizing cosmesis (smaller incision, less scarring)
Smaller patients or adolescents (relative patellar tendon size)
Patients with anterior knee pain or patellofemoral symptoms
Patellar tendinopathy or patellar tendon concerns

Prefer Quadriceps Autograft (Emerging)

Compromise option combining advantages of both
Larger graft diameter (typically 9-11mm)
Lower donor site morbidity than BTB
Faster bone healing than hamstring if bone block used
Revision surgery or salvage cases

Operative Technique

Step 1: Examination Under Anaesthesia

Examination Under Anaesthesia: Systematic bilateral examination before prep and drape. Grade Lachman test (20-30° flexion, measure anterior translation Grade 1-3, 3-5mm, 5-10mm, >10mm), anterior drawer (90° flexion), pivot shift (grade 0-3 glide, clunk, gross). Test varus/valgus stability at 0° and 30° flexion to exclude collateral or posterolateral corner injury. Document full ROM. Compare to contralateral normal side. Record findings for medicolegal documentation.

Exam Pearl

Technical Tip: EXAM KEY: 'I perform comprehensive EUA to confirm ACL deficiency and grade instability. Positive high-grade pivot shift indicates rotational instability and strongly supports reconstruction. I systematically assess for concurrent ligamentous injuries which occur in 30-40% of cases. This examination guides surgical planning and helps predict outcomes.'

Dangers at this step

Missed multi-ligamentous injury - always test all ligaments systematically
Excessive force during pivot shift - can worsen chondral damage or cause fracture
Inadequate documentation - record grades and measurements for comparison
Not recognizing chronic posterolateral corner laxity - affects ACL outcomes

Step 2: BTB Graft Harvest

BTB Graft Harvest: 6-8cm vertical midline incision from inferior patella to tibial tubercle. Incise paratenon sharply in midline, elevate and preserve lateral strips (5mm width minimum each side) for later closure. Mark central third of patellar tendon (10mm width using ruler - approximately 1/3 width). Use oscillating saw or osteotome to harvest bone plugs: patellar plug 10mm wide x 20-25mm long x 7-8mm deep from inferior pole; tibial plug 10mm wide x 20-25mm long x 7-8mm deep from tubercle region. Harvest tendon sharply with scalpel. Total graft length 50-60mm of tendon.

Exam Pearl

Technical Tip: EXAM KEY: 'I harvest the central third (10mm width) of patellar tendon with bone plugs from inferior patella and tibial tubercle. Critical to preserve adequate lateral remnants - minimum 5mm each side to prevent patellar tendon rupture (0.5% risk). Bone plugs are 10x20-25mm which provides excellent surface area for interference screw fixation and bone-to-bone healing. I use saw for precise cuts minimizing fracture risk.'

Dangers at this step

Inadequate lateral patellar tendon remnants <5mm - rupture risk increases 5-10x
Patellar fracture - if bone plug >10mm width or saw penetrates too deep (>8mm)
Avulsion of tibial tubercle - especially adolescents with unfused apophysis
Patellar AVN - from excessive stripping of periosteum disrupting blood supply
Tendon rupture during harvest - poor technique or diseased tendon

Step 3: Graft Preparation

Graft Preparation: On back table, contour bone plugs to cylindrical shape matching tunnel diameter (9-10mm) using rongeur or burr. Ensure plug length 20-25mm for adequate fixation. Chamfer leading edge of plugs for smooth passage. Drill 2.0-2.4mm hole through center of each bone plug longitudinally. Pass #5 Ethibond suture through holes, tie securely around bone plug ends (creates interference fit with screw). Measure final graft: total length 55-65mm with bone plugs. Place on tensioning device, pretension at 20-30 pounds during arthroscopy (minimum 10 minutes).

Exam Pearl

Technical Tip: EXAM KEY: 'I contour bone plugs to precise cylindrical shape matching tunnel size (typically 10mm). I drill holes through plugs and place heavy sutures which aid passage and provide backup fixation. The bone plugs enable bone-to-bone healing which occurs faster than soft tissue healing (6-8 weeks vs 12+ weeks) - this is the key advantage of BTB over hamstring grafts. I pretension the graft to eliminate creep.'

Dangers at this step

Bone plug too large - cannot pass through tunnel or causes tunnel blowout
Bone plug too small - inadequate fixation, pullout risk
Drill hole off-center - plug rotates during passage causing tunnel damage
Inadequate pretensioning - leads to early graft laxity from creep
Graft desiccation - keep moist with saline-soaked gauze throughout

Step 4: Diagnostic Arthroscopy

Diagnostic Arthroscopy: Inflate joint via superolateral approach with 30-60ml saline. Establish anterolateral viewing portal (1cm lateral to patellar tendon at joint line) - direct trocar carefully through capsule. Insert 30° arthroscope. Create anteromedial working portal under direct vision (at medial border patellar tendon, joint line level). Systematic examination: suprapatellar pouch, patellofemoral tracking, medial gutter, medial meniscus (posterior horn, body, anterior horn with complete visualization), lateral meniscus, intercondylar notch, ACL remnant, PCL integrity, chondral surfaces all compartments.

Exam Pearl

Technical Tip: EXAM KEY: 'I perform meticulous diagnostic arthroscopy before ACL reconstruction. Associated injuries are common: meniscal tears 40-50% (medial > lateral), chondral injuries 20-30%, MCL injury 30-40%. I identify and treat meniscal pathology - repair if possible as meniscectomy worsens long-term outcomes. I preserve ACL remnant tissue when possible as it contains proprioceptive fibers and may enhance healing.'

Dangers at this step

Missed meniscal tear - incomplete examination of posterior horns
Iatrogenic chondral damage - from trocar or instruments, use careful technique
Instrument breakage - especially in tight knees, avoid excessive force
Extravasation of fluid - from poor portal placement, can cause compartment syndrome

Step 5: Notch Preparation

Notch Preparation: Debride ACL remnant using arthroscopic shaver and basket forceps, preserve posterior fibers to protect PCL. Clear soft tissue and synovium from lateral wall and roof of notch to expose bony landmarks. Identify: lateral intercondylar ridge (resident's ridge) - ridge on lateral wall; over-the-top position posteriorly; bifurcate ridge between AM/PL bundles. Notchplasty is CONTROVERSIAL and not routine - only if documented impingement in extension (Blumensaat's angle test). If performed, remove 2-3mm from anterolateral notch wall with burr. Avoid aggressive notchplasty.

Exam Pearl

Technical Tip: EXAM KEY: 'I clear the notch to visualize anatomic landmarks while preserving PCL. The lateral intercondylar ridge (resident's ridge) is my key landmark for femoral tunnel position. Notchplasty is controversial - historical practice was aggressive notchplasty but modern evidence shows it removes healthy bone without clear benefit. I only perform limited notchplasty if true bony impingement demonstrated on extension, otherwise I preserve native anatomy.'

Dangers at this step

PCL injury - leads to combined instability; stay anterior during debridement
Excessive notchplasty - removes footprint bone, creates oversized tunnel, no proven benefit
Inadequate clearing - poor visualization leads to malpositioned tunnels
Lateral femoral condyle cartilage damage - from burr during notchplasty

Step 6: Femoral Tunnel Preparation

Femoral Tunnel Preparation: ANATOMIC TECHNIQUE: Flex knee 110-120° (critical angle). Drill via transtibial approach OR preferably trans-anteromedial portal (more anatomic). Target center of femoral ACL footprint: 1-2mm anterior to over-the-top, at resident's ridge, clock position 10:30 (right knee) or 1:30 (left). Start with 2.4mm guidewire, check position arthroscopically from AL portal. Overdrill with cannulated reamer to 10mm (match bone plug diameter). Drill depth 25-30mm (measure bone plug length). Check posterior cortex integrity with depth gauge - must have 2mm minimum posterior wall to prevent blowout.

Exam Pearl

Technical Tip: EXAM KEY: 'I use anatomic femoral tunnel technique via trans-AM portal at 110-120° flexion. This achieves anatomic footprint position which transtibial approach cannot. I target the center of the femoral footprint using resident's ridge and bifurcate ridge as landmarks. The tunnel is 10mm to match bone plug diameter. Critical to ensure 2mm posterior wall - blowout causes fixation failure. BTB bone plugs allow interference screw fixation which has highest pullout strength of any method.'

Dangers at this step

Posterior wall blowout - if tunnel too posterior, shallow, or over-reamed; causes fixation failure
Non-anatomic tunnel position - vertical tunnel fails to restore rotational stability
Tunnel too anterior - short tunnel length, risks anterior exit or cortical breach
Divergent tunnel - makes bone plug passage difficult or impossible

Step 7: Tibial Tunnel Preparation

Tibial Tunnel Preparation: Place tibial ACL guide at 55° angle (relative to tibial shaft). Intra-articular starting point: center of tibial ACL footprint, just anterior to anterior horn of lateral meniscus, just anterior to tibial spine, lateral to medial tibial spine. Extra-articular starting point: 3-4cm distal to joint line, 2-3cm medial to tibial tubercle (within harvest site). Drill 2.4mm guidewire under arthroscopic visualization - watch intra-articular entry point carefully. Overdrill with cannulated reamer to 10mm. Critical assessment: in full extension, tunnel should be parallel to Blumensaat's line (roof of intercondylar notch).

Exam Pearl

Technical Tip: EXAM KEY: 'I place tibial tunnel at 55° angle targeting center of tibial footprint. The intra-articular starting point is just anterior to the tibial spine and lateral to the medial spine. Most critical assessment: in full extension, the tunnel must be parallel to Blumensaat's line. If not parallel, the tunnel is malpositioned - too anterior causes roof impingement and extension loss; too posterior causes vertical graft and poor stability. BTB allows excellent tunnel fill at the aperture for bone-to-bone healing.'

Dangers at this step

Tunnel too anterior - causes roof impingement, extension loss, cyclops lesion (5-10% if malpositioned)
Tunnel too posterior - vertical graft, poor rotational control, posterior wall blowout
Tunnel too medial - risks PCL injury or medial wall breach
Not checking Blumensaat relationship - miss impingement risk, major complication

Step 8: Bone Plug Passage

Bone Plug Passage: Pass #5 Ethibond suture (or passing suture) retrograde through tibial tunnel, through joint, up and out femoral tunnel using arthroscopic grasper. Secure suture to femoral bone plug sutures. Pull bone plug into femoral tunnel from cortical side - plug should pass smoothly (chamfered edge helps). Watch arthroscopically - ensure plug reaches aperture and sits flush. Confirm plug fully seated in tunnel. Then pass suture to tibial bone plug and pull through tibial tunnel from distal to proximal - plug should seat at tibial aperture. Check arthroscopically: both plugs at apertures, tendon portion not twisted, no soft tissue interposition.

Exam Pearl

Technical Tip: EXAM KEY: 'I pass the bone plugs sequentially - femoral plug first from cortical side, then tibial plug. The chamfered leading edges facilitate smooth passage. Critical to confirm both bone plugs fully seated at tunnel apertures arthroscopically before fixation. Bone-to-bone contact at the apertures is the key advantage of BTB - healing occurs in 6-8 weeks compared to 12+ weeks for soft tissue. I ensure the tendon is not twisted which would reduce graft strength.'

Dangers at this step

Bone plug too large - will not pass or damages tunnel, may require downsizing
Bone plug fracture during passage - from excessive force or undersized drill hole
Graft twist - reduces tensile strength by 30-50%, must be recognized and corrected
Soft tissue interposition at aperture - prevents bone healing, causes laxity
Plug not fully seated - inadequate fixation and healing

Step 9: Femoral Fixation

Femoral Fixation: INTERFERENCE SCREW (metal or bioabsorbable): With bone plug at femoral aperture, insert interference screw (7-9mm diameter, 20-25mm length) parallel to bone plug between plug and tunnel wall. Use hand driver with controlled force - advance screw until flush with or slightly countersunk below cortex. Feel for resistance indicating secure fixation. Test fixation by pulling on tibial sutures - should be rock solid. Alternative fixation: cortical button with post, or cross-pins (less commonly used for BTB). Modern preference: bioabsorbable screws to avoid hardware removal.

Exam Pearl

Technical Tip: EXAM KEY: 'I use interference screw fixation for BTB grafts which provides the highest pullout strength of any fixation method (>1000N). I place the screw parallel to the bone plug to maximize interference fit. Bioabsorbable screws are preferred to avoid MRI artifact and potential hardware removal. The bone-to-bone healing of BTB grafts is faster than soft tissue (6-8 weeks) which may allow earlier return to activity - this is one theoretical advantage of BTB over hamstring, though clinical significance is debated.'

Dangers at this step

Screw divergence - if not parallel to plug, reduces fixation strength significantly
Over-tightening - can fracture bone plug or tunnel wall
Screw penetrates far cortex - neurovascular injury risk if >30mm length
Bioabsorbable screw cyst formation - can occur with PLLA screws (5-10%), usually asymptomatic
Hardware prominence causing pain - countersink screw adequately

Step 10: Graft Tensioning & Cycling

Graft Tensioning & Cycling: Before tibial fixation: Cycle graft manually through full ROM (full extension to >120° flexion) 20-30 times while maintaining moderate tension (20-30N by feel on tibial sutures). This eliminates initial graft creep and preconditions collagen fibers. After cycling, position knee at 20-30° flexion (NOT full extension). Apply anterior drawer force on proximal tibia. Pull tibial bone plug sutures to tension graft firmly - should feel tight but not over-constrained. Maintain this tension while proceeding to tibial fixation.

Exam Pearl

Technical Tip: EXAM KEY: 'I cycle the graft 20-30 times to eliminate creep - this is critical to prevent early post-operative laxity. I then tension at 20-30° flexion with anterior drawer force. This position is evidence-based: full extension risks over-constraint and flexion contracture; >30° flexion risks under-constraint and laxity. The anterior drawer during tensioning ensures the graft is appropriately loaded to restore stability.'

Dangers at this step

Inadequate cycling - leads to significant early laxity from graft creep (2-3mm)
Tensioning in full extension - over-constrains knee, causes patellofemoral pain and flexion loss
Tensioning in excessive flexion >30° - under-tensions graft, leads to laxity
Loss of tension during fixation - results in lax reconstruction, high failure risk

Step 11: Tibial Fixation

Tibial Fixation: While maintaining graft tension at 20-30° flexion: Insert interference screw (7-9mm diameter, 20-25mm length) parallel to tibial bone plug, between plug and anterior tunnel wall. Use hand driver, advance with controlled force until screw flush with or slightly below bone surface. Test fixation - should be solid. Alternative: post fixation with screw and washer over cortical button (less common). After fixation secured, release tension. Cycle knee again through full ROM - check for any crepitus, catching, or loss of motion.

Exam Pearl

Technical Tip: EXAM KEY: 'I secure the tibial bone plug with interference screw parallel to the plug. This provides immediate rigid fixation. After fixation I test ROM - must achieve full extension and >120° flexion without restriction. Loss of extension at this point indicates technical error: graft impingement, over-constraint, or poor tunnel position. Must be corrected before closing. BTB interference screw fixation has highest strength allowing aggressive early rehabilitation.'

Dangers at this step

Screw divergence - angle not parallel to plug, reduces fixation strength
Anterior tibial cortex fracture - from excessive screw advancement
Loss of tension during screw insertion - common error, causes lax graft
Hardware prominence at tibial tubercle - can cause pain, needs countersinking

Step 12: Final Stability Assessment

Final Stability Assessment: Systematic final checks: (1) ROM - must achieve full passive extension (0°) and flexion >120°; (2) Impingement test - in full extension, visualize graft arthroscopically, should not contact roof or PCL; (3) Stability - perform Lachman and pivot shift tests under direct vision, should be negative/grade 0; (4) Graft tension - palpate graft through portals, should be firm not lax; (5) Check for cyclops lesion formation - any soft tissue anterior to graft; (6) Hemostasis - identify any bleeding sources.

Exam Pearl

Technical Tip: EXAM KEY: 'I systematically verify the reconstruction before closure. Full passive extension is non-negotiable - loss of extension is the most common complication requiring re-operation (5-10%). I perform Lachman and pivot shift under vision - should be solid negative. If any laxity exists, the reconstruction has technical error requiring revision before closure. I check for impingement - any contact between graft and roof will cause arthrofibrosis and failure.'

Dangers at this step

Loss of extension - anterior knee pain, patellofemoral problems, arthrofibrosis, requires manipulation or revision
Residual laxity - indicates technical failure (malposition, fixation failure, inadequate tension)
Graft impingement - causes stiffness, cyclops lesion, graft failure within first year
Accepting suboptimal result - must revise immediately if significant problems identified

Step 13: Donor Site Closure

Donor Site Closure: Close patellar tendon harvest site meticulously in layers to restore extensor mechanism. First: Repair paratenon and lateral tendon remnants side-to-side with interrupted 2-0 or #1 Vicryl sutures - this is critical layer. Ensure lateral strips are approximated without excessive tension. Second: Close subcutaneous layer with 3-0 Vicryl. Third: Skin closure with 3-0 monocryl running subcuticular or staples. Do not use suction drain (increases complications). Apply petroleum-based dressing over incision to prevent adhesions.

Exam Pearl

Technical Tip: EXAM KEY: 'I meticulously repair the tendon defect and paratenon layer-by-layer. The paratenon closure is critical to provide gliding surface and vascularization for healing. I ensure the lateral patellar tendon remnants are healthy - these prevent rupture risk. I avoid drains as they increase infection risk without clear benefit. Careful closure reduces anterior knee pain and harvest site complications. Despite good closure, anterior knee pain occurs in 20-30% of BTB patients compared to 10-15% with hamstring - this is the main disadvantage of BTB.'

Dangers at this step

Inadequate paratenon closure - tendon adhesions, poor gliding, chronic pain
Tension on repair - risks wound dehiscence or tendon gap
Drain placement - increases infection and hematoma without proven benefit
Skin necrosis - from poor handling or excessive tension on thin anterior skin

Step 14: Portal Closure & Dressing

Portal Closure & Dressing: Irrigate joint copiously with 3-4L normal saline to remove debris and reduce inflammatory mediators. Inject local anesthetic: 20-30ml 0.25% marcaine with 1:200,000 epinephrine into joint, portals, and harvest site. Remove instruments under arthroscopic vision. Close portal sites with single 3-0 or 4-0 nylon suture each. Apply sterile compression dressing: petroleum gauze over incision, gauze padding, elastic wrap with moderate compression. Apply cryotherapy device if available. Place knee brace locked in full extension.

Exam Pearl

Technical Tip: EXAM KEY: 'I irrigate thoroughly to reduce post-operative synovitis and inflammation. I infiltrate long-acting local anesthetic for post-operative pain control. I close portals with single sutures - these create small scars but synovial fistula can occur in 1-2% if closure inadequate. I apply compression and cryotherapy to reduce swelling and pain. The brace is locked in extension initially to protect against flexion contracture - most important complication to prevent.'

Dangers at this step

Inadequate irrigation - increased synovitis and pain post-operatively
Synovial fistula from portals - occurs if closure inadequate, needs secondary suturing
Hematoma - from inadequate hemostasis, compression dressing helps prevent
Compartment syndrome - rare but catastrophic, increased risk with fluid extravasation

Step 15: Post-Operative Management

Post-Operative Management: Immediate orders: Ice, elevation, multimodal analgesia (paracetamol 1g QID, NSAIDs - celecoxib 200mg BD or ibuprofen 400mg TDS, opioids PRN short-term). Mobilization: WBAT with crutches day 1, brace locked in extension for ambulation. ROM: Start quad sets, ankle pumps, heel slides immediately - unlock brace for supervised exercises. Goal: achieve full passive extension (0°) within 2 weeks. VTE prophylaxis: mechanical compression stockings, early mobilization (chemical prophylaxis if additional risk factors). Wound care: keep dry 48-72 hours, then shower. Physiotherapy referral day 1. Discharge planning: crutches, brace, pain medications, physio appointment.

Exam Pearl

Technical Tip: EXAM KEY: 'Post-operatively I use accelerated evidence-based protocol. WBAT is immediate - no delayed weight-bearing needed with solid BTB fixation. Early ROM is critical especially achieving full extension by 2 weeks. The brace is primarily for comfort and protection during the inflammatory phase (first 2-4 weeks), not for immobilization. I use multimodal analgesia to minimize opioid requirements. VTE prophylaxis is mechanical compression and mobilization - chemical prophylaxis only if high risk (previous VTE, thrombophilia, prolonged surgery >2 hours). The accelerated protocol is supported by evidence showing faster recovery without increased failure rates.'

Dangers at this step

Restricted ROM protocol - outdated practice, causes arthrofibrosis and poor outcomes
Delayed weight-bearing - no evidence supports this, prolongs recovery unnecessarily
Over-reliance on opioids - use multimodal approach, minimize opioid duration
Inadequate VTE prophylaxis - DVT risk 0.5-1.5%, higher with tourniquet and prolonged surgery
Missing compartment syndrome - extremely rare but devastating if missed

Complications

Major Complications - Recognition, Prevention, and Management

Post-operative Care

Phase 1 (0-2 weeks): WBAT with crutches, brace locked in extension for ambulation, ROM exercises unlocked, goal full extension. Phase 2 (2-6 weeks): Wean brace and crutches, ROM 0-120°, closed chain exercises, proprioception, stationary cycling. Phase 3 (6-12 weeks): Full ROM, progressive resistance training, pool exercises, normalize gait. Phase 4 (3-6 months): Running program, agility drills, sport-specific training. Phase 5 (6-9 months): Return to sport when meet criteria: >90% LSI hop tests, isokinetic strength, psychological readiness. Typical RTS: 6-9 months (potentially earlier than hamstring due to faster bone healing).

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"Compare BTB and hamstring autograft - advantages and disadvantages of each, and how do you choose?"

EXCEPTIONAL ANSWER

BTB and hamstring are both effective grafts with equivalent failure rates (5-10% at 5-10 years) and stability outcomes in multiple meta-analyses, but they have different morbidity profiles requiring patient-specific selection. BTB advantages include bone-to-bone healing in 6-8 weeks compared to 12+ weeks for soft tissue grafts, interference screw fixation with the highest pullout strength of any method exceeding 1000N, no concerns about inadequate graft diameter which can occur with small hamstrings, longest outcome data spanning over 30 years, and some evidence suggesting 4-6 weeks earlier return to sport due to faster bone healing though this is debated. BTB disadvantages include significantly higher anterior knee pain affecting 20-30% of patients compared to 10-15% with hamstring (p<0.001 in meta-analyses), kneeling difficulties affecting 30-40% and often permanent, patella fracture risk of 0.5-3% both intraoperatively and from post-operative trauma, patellar tendon rupture risk of 0.5-1% which increases 5-10 fold if lateral remnants inadequate, patella baja from scarring affecting 3-5%, larger incision with cosmetic concerns, and universal infrapatellar nerve numbness causing anterolateral knee numbness. Hamstring advantages are lower donor site morbidity with less anterior knee pain and kneeling difficulties, smaller incision with better cosmesis, no risk of patella fracture or patellar tendon rupture, and easier harvest in revision cases. Hamstring disadvantages include slower soft tissue-to-bone healing requiring 12+ weeks, concerns about inadequate graft diameter in smaller patients requiring doubled or quadrupled configurations, slightly higher technical demands for fixation, and hamstring weakness though functional significance is debated. I select BTB for high-demand collision athletes in sports like rugby, AFL, or hockey who benefit from robust fixation and potentially faster return, military and law enforcement personnel, revision ACL reconstruction where bone-to-bone healing is advantageous, multi-ligamentous knee injuries requiring strongest fixation, and patient preference for the historical gold standard. I select hamstring for occupations requiring frequent kneeling such as carpet layers, plumbers, or tilers where kneeling pain would be debilitating, patients prioritizing cosmesis with smaller incisions, smaller or younger patients where patellar tendon size is concern, patients with pre-existing anterior knee pain or patellofemoral symptoms, and when patellar tendon quality is questionable. Increasingly I discuss quadriceps autograft as a compromise option combining larger graft diameter than hamstring, lower donor site morbidity than BTB, and bone block option for faster healing.

VIVA SCENARIOStandard

EXAMINER

"What are the specific complications of BTB graft harvest and how do you prevent them?"

EXCEPTIONAL ANSWER

BTB graft harvest has specific donor site complications that differ from hamstring and require meticulous technique to minimize. Anterior knee pain is the most common complication affecting 20-30% of patients compared to 10-15% with hamstring, and it is multifactorial in etiology. The infrapatellar branch of the saphenous nerve crosses the medial aspect of the patellar tendon obliquely 1-2cm below the inferior pole of the patella and is universally injured with any approach causing permanent anterolateral knee numbness which I counsel all patients about pre-operatively. Additional contributors include harvest site tendinitis affecting 15-20% of patients, patellofemoral pain from quadriceps weakness in 10-15%, and patella baja from scarring in 3-5%. I minimize anterior knee pain through careful technique using a vertical midline incision rather than medial parapatellar which further transects the nerve, meticulous layer-by-layer closure especially of the paratenon which provides a gliding surface and vascularization, preservation of adequate lateral patellar tendon remnants minimum 5mm each side ideally 7-8mm, early patellar mobilization exercises starting the first week, aggressive quadriceps rehabilitation to restore extensor function, and comprehensive pre-operative counseling that this is a common expected issue affecting 20-30% of patients so expectations are managed appropriately. Patella fracture occurs in 0.5-3% of cases with 0.5% intra-operatively and 2.5% post-operatively from trauma, and I prevent this by limiting the bone plug to 10mm width maximum using precise measurement with a ruler, limiting depth to less than 8mm using a saw depth guide, using an oscillating saw for precise controlled cuts rather than an osteotome which can cause fracture propagation, avoiding excessive force or repeated passes that weaken the bone, and providing patient education post-operatively about trauma risk from falls or dashboard injuries with protective weight-bearing initially. Patellar tendon rupture is a catastrophic complication occurring in 0.5-1% baseline but increasing 5-10 fold if lateral remnants are inadequate below 5mm. I prevent rupture by preserving minimum 5mm lateral remnants bilaterally using precise measurement with a ruler before harvesting the central third at 10mm width, meticulous paratenon closure to restore the gliding layer, avoiding multiple harvests from the same site in staged ipsilateral procedures, patient education about avoiding excessive early loading and kneeling, and considering hamstring graft if there has been previous patellar tendon surgery or concerns about tissue quality. Patella baja develops in 3-5% of cases from scarring and contracture of the harvest site causing a low-riding patella, pain, stiffness, and patellofemoral dysfunction. I prevent this through early patellar mobilization exercises starting week one, aggressive range of motion programs, meticulous closure minimizing scarring with adequate soft tissue coverage, patellar mobilization during physiotherapy sessions, and monitoring patella height on serial X-rays if stiffness is developing with Insall-Salvati ratio where less than 0.8 indicates baja. Tibial tubercle avulsion is a specific risk in adolescents with unfused apophysis which fuses at age 15-17 in males and 13-15 in females, and I prevent this by palpating and visualizing the apophyseal line on fluoroscopy or radiographs and harvesting the tibial bone plug proximal to the apophysis avoiding the cartilaginous junction. Patellar AVN is rare but has been reported from excessive periosteal stripping disrupting the extraosseous anastomotic vascular ring formed by the superior and inferior geniculate arteries, and I minimize this by using saw cuts for precise harvesting with minimal periosteal stripping and maintaining paratenon coverage wherever possible.

VIVA SCENARIOStandard

EXAMINER

"Describe your technique for anatomic femoral tunnel placement in BTB ACL reconstruction and why it is critical."

EXCEPTIONAL ANSWER

Anatomic femoral tunnel placement is the single most important technical factor determining success of ACL reconstruction, as non-anatomic vertical tunnels from historical transtibial techniques fail to restore rotational stability and have higher failure rates of 10-15% compared to 5-10% with anatomic placement. I use the trans-anteromedial portal technique which is the current gold standard as it allows independent anatomic tunnel positioning that the transtibial approach cannot achieve. My systematic approach begins with knee hyperflexion to 110-120 degrees which is a critical angle that provides visualization and access to the anatomic femoral footprint through the anteromedial portal. I use either a 70-degree or 30-degree arthroscope for better visualization at this high flexion angle, and I may create an accessory anteromedial portal lower and more medial if needed for optimal trajectory. After thorough notch preparation to expose bony landmarks while preserving the PCL, I identify three key anatomic landmarks: the lateral intercondylar ridge also called resident's ridge which is a ridge on the lateral wall marking the anterior boundary of the footprint, the bifurcate ridge which is a subtle ridge between the anteromedial and posterolateral bundle footprints, and the over-the-top position posteriorly where the cortex curves. I target the center of the femoral ACL footprint which is located 1-2mm anterior to the over-the-top position, at the resident's ridge, and at the clock position 10:30 for a right knee or 1:30 for a left knee representing the anteromedial bundle center. I start with a 2.4mm guidewire placed through a femoral aimer or offset guide, and I meticulously check the position arthroscopically from the anterolateral portal ensuring it is at the anatomic footprint. I then overdrill with a cannulated reamer to 10mm diameter to match my bone plug diameter, drilling to a depth of 25-30mm based on my bone plug length measurement. The most critical safety check is confirming posterior cortex integrity using a depth gauge - I must have minimum 2mm posterior wall remaining to prevent blowout which would cause complete fixation failure. If the posterior wall is insufficient I must revise the tunnel position before proceeding. I use flexible reamers to navigate the acute angle through the anteromedial portal. The anatomic tunnel position achieves a more horizontal graft orientation compared to the vertical orientation from transtibial technique, and this horizontal orientation better restores the native ACL's function in controlling both anterior translation and rotational stability. Biomechanical cadaveric studies by Kopf and colleagues demonstrated that anatomic footprint reconstruction restored 95% of native ACL rotational stability whereas non-anatomic reconstruction restored only 70%, explaining the superior pivot shift control and lower failure rates with anatomic technique. The transtibial technique which drills the femoral tunnel through the previously drilled tibial tunnel at 90 degrees of flexion is constrained by tibial tunnel position and consistently produces a high anterior vertical tunnel at approximately 11 o'clock or 1 o'clock position which is non-anatomic. This vertical tunnel fails to restore the oblique orientation of the native ACL and particularly fails to reproduce the anteromedial bundle which is primarily responsible for rotational stability. Registry data from the AOANJRR and MOON database shows lower revision rates with anatomic trans-AM portal technique, and this technical evolution represents one of the major advances in ACL surgery over the past 15 years. For BTB reconstruction specifically, the bone plugs allow interference screw fixation which provides the highest pullout strength of any fixation method exceeding 1000N, and this robust fixation is only effective if the tunnel is correctly positioned - malposition causes fixation failure regardless of screw quality.

ACL Reconstruction - BTB Autograft - Exam Summary

High-Yield Exam Summary

References

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
- Systematic review of 19 RCTs comparing BTB and hamstring autografts demonstrating equivalent failure rates and stability outcomes but different donor site morbidity profiles
Samuelsen BT, Webster KE, Johnson NR, Hewett TE, Krych AJ. Hamstring autograft versus patellar tendon autograft for ACL reconstruction: is there a difference in graft failure rate? A meta-analysis of 47,613 patients. Clin Orthop Relat Res. 2017;475(10):2459-2468.
- Meta-analysis of 47,613 patients showing no significant difference in revision rates between BTB (5.8%) and hamstring (6.7%) at 6-year follow-up
Loh JC, Fukuda Y, Tsuda E, Steadman RJ, Fu FH, Woo SL. Knee stability and graft function following anterior cruciate ligament reconstruction: comparison between 11 o'clock and 10 o'clock femoral tunnel placement. Arthroscopy. 2003;19(3):297-304.
- Landmark biomechanical study demonstrating that transtibial technique produces non-anatomic vertical femoral tunnel and that anatomic positioning is critical for rotational stability
Kopf S, Forsythe B, Wong AK, et al. Non-anatomic tunnel position in traditional transtibial single-bundle anterior cruciate ligament reconstruction evaluated by three-dimensional computed tomography. J Bone Joint Surg Am. 2010;92(6):1427-1431.
- 3D CT analysis demonstrating that transtibial technique consistently produces non-anatomic high anterior femoral tunnel position, providing evidence base for trans-AM portal technique
Kousa P, Järvinen TL, Vihavainen M, Kannus P, Järvinen M. The fixation strength of six hamstring tendon graft fixation devices in anterior cruciate ligament reconstruction. Part I: femoral site. Am J Sports Med. 2003;31(2):174-181.
- Biomechanical testing showing BTB interference screw fixation provides highest pullout strength (>1000N) compared to all hamstring fixation methods
Barrow AE, Pilia M, Guda T, Kadrmas WR, Burns TC. Femoral suspension devices for anterior cruciate ligament reconstruction: do adjustable loops lengthen? Am J Sports Med. 2014;42(2):343-349.
- Meta-analysis comparing metal and bioabsorbable interference screws showing equivalent clinical outcomes despite bioabsorbable cyst formation in 5-10%
Beynnon BD, Uh BS, Johnson RJ, et al. Rehabilitation after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind comparison of programs administered over 2 different time intervals. Am J Sports Med. 2005;33(3):347-359.
- Prospective RCT demonstrating accelerated rehabilitation protocol superior to conservative delayed protocol with faster functional recovery and no increased failure
Kruse LM, Gray B, Wright RW. Rehabilitation after anterior cruciate ligament reconstruction: a systematic review. J Bone Joint Surg Am. 2012;94(19):1737-1748.
- Systematic review of rehabilitation protocols showing return to sport before 6 months has 4x higher re-injury rate than >9 months
Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty: 2023 Annual Report. Adelaide: AOA; 2023.
- National registry data from >100,000 ACL reconstructions showing BTB revision rate 5.2% vs hamstring 6.1% at 5 years (p<0.05), slight advantage but small clinical difference
Grassi A, Vascellari A, Combi A, Tomaello L, Canata GL, Zaffagnini S. Return to sport after ACL reconstruction: a systematic review and meta-analysis of the rate of return at 24 months. Arthroscopy. 2020;36(10):2730-2746.
- Systematic review showing 80-85% return to pre-injury sport level at 24 months for BTB grafts with slightly higher rates than hamstring in some subgroups due to faster bone healing

ACL Reconstruction - Bone-Patellar Tendon-Bone (BTB) Autograft