ACL Reconstruction Technique

Bone-Patellar Tendon-Bone (BTB):

Advantages:

• Bone-to-bone healing in tunnels (faster, stronger integration)
• Some evidence of lower re-rupture in young athletes
• Historical "gold standard"

Disadvantages:

• Anterior knee pain (up to 20%)
• Kneeling pain
• Risk of patellar fracture, tendon rupture
• Fixed graft size

Use: First-time ACL reconstruction in young athletes, particularly if early return to high-level sport is priority.

Hamstring Autograft (Semitendinosus +/- Gracilis):

Advantages:

• Less anterior knee pain
• Smaller incision
• Variable graft diameter (can quadruple)

Disadvantages:

• Soft tissue to bone healing (slower)
• Graft may be small (less than 8mm increases failure)
• Some hamstring weakness
• Tunnel widening

Use: First-time reconstruction, athletes without high anterior knee pain risk, patients concerned about kneeling.

Quadriceps Tendon:

• Full or partial thickness
• Growing popularity
• Bone block option
• Good size

Allograft:

• Useful in revision
• Older, lower-demand patients
• Higher failure in young athletes
• No donor site morbidity

Allograft is best reserved for revision surgery or low-demand patients.

Two Functional Bundles:

1. Anteromedial (AM) Bundle:

   • More anterior and proximal femoral attachment
   • Taut in flexion
   • Primary restraint to anterior tibial translation
   • Guides surgical technique in single-bundle reconstruction

2. Posterolateral (PL) Bundle:

   • More posterior and distal femoral attachment
   • Taut in extension
   • Controls rotational stability
   • Contributes to pivot shift phenomenon

Functional Significance: AM bundle controls anteroposterior stability; PL bundle controls rotational stability. Single-bundle reconstruction aims to replicate combined function.

Femoral Attachment:

• Located on posteromedial aspect of lateral femoral condyle
• Semicircular shape, approximately 18mm long
• Resident's ridge: Bony landmark marking anterior border
• Lateral intercondylar ridge: Proximal border
• Direct (ligamentous) and indirect (fibrocartilage) insertions

Surgical Relevance:

• Single-bundle reconstruction targets center of footprint
• Double-bundle targets centers of AM and PL bundles separately
• Posterior to resident's ridge is critical landmark

Tibial Attachment:

• Broad, oval-shaped depression on anterior tibial plateau
• Located between tibial spines
• Area approximately 120-150 mm²
• Posterior to anterior horn of lateral meniscus
• Lateral to medial tibial spine

Surgical Landmarks:

• Behind intersection of ACL stump and lateral meniscus
• Center of footprint is surgical target
• Anterior placement causes roof impingement

ACL Injury Grades:

Clinical Testing:

• Lachman test: Most sensitive (95%) - Grade 1 (3-5mm), Grade 2 (5-10mm), Grade 3 (greater than 10mm)
• Anterior drawer: Less sensitive than Lachman
• Pivot shift: Most specific for rotational instability

Classification by Technique:

1. By Graft Type:

   • Autograft: BTB, hamstring, quadriceps
   • Allograft: Tibialis, Achilles, hamstring

2. By Bundle Number:

   • Single-bundle (most common)
   • Double-bundle (AM + PL)

3. By Femoral Drilling:

   • Transtibial (historical)
   • Transportal (current standard)
   • Outside-in (independent positioning)

4. By Approach:

   • Primary reconstruction
   • Revision reconstruction
   • Augmentation with lateral tenodesis

ACL Injury Patterns:

Bone Bruising Pattern: Kissing contusions of lateral femoral condyle and posterolateral tibial plateau - pathognomonic of ACL injury on MRI.

Standard Radiographs (AP, lateral, skyline):

Acute Findings:

• Usually normal
• Segond fracture: Avulsion of lateral tibial plateau rim - pathognomonic of ACL injury
• Tibial spine avulsion: Especially in adolescents
• Lateral capsular sign

Pre-operative Assessment:

• Joint space narrowing (osteoarthritis)
• Tunnel position from prior surgery (revision cases)
• Notch width: Narrow notch may increase impingement risk
• Limb alignment (varus/valgus)

Post-operative:

• Tunnel position assessment
• Hardware position
• Tunnel widening (follow-up)

Gold Standard for ACL Injury Diagnosis:

Primary Signs of ACL Rupture:

• Non-visualization of ACL fibers
• Discontinuity of fibers
• Abnormal signal intensity
• Horizontal fiber orientation (normally oblique)

Secondary Signs:

• Bone bruise pattern: Lateral femoral condyle + posterolateral tibial plateau (pathognomonic)
• Anterior tibial translation
• Uncovering of posterior horn lateral meniscus
• Deep lateral femoral notch sign (greater than 1.5mm)
• PCL buckling

Associated Pathology Assessment:

• Meniscal tears (40-60% of ACL injuries)
• Collateral ligament injury
• Chondral damage
• Posterolateral corner injury

CT Scan:

• Useful for revision surgery - assess tunnel position and size
• 3D reconstruction for complex cases
• Tibial spine fracture assessment

Stress Radiographs:

• KT-1000/KT-2000 arthrometer: Objective measurement of anterior translation
• Side-to-side difference greater than 3mm is significant
• Used in research and some clinical settings

Diagnostic Arthroscopy:

• Rarely indicated purely for diagnosis (MRI usually sufficient)
• Performed at time of reconstruction
• Allows assessment and treatment of associated pathology

Indications for Non-operative Management:

• Low-demand patients
• Older, sedentary individuals
• No symptomatic instability
• Willing to modify activities
• Partial tears with minimal laxity

Non-operative Protocol:

1. Acute Phase (0-2 weeks):

   • RICE protocol
   • Protected weight-bearing
   • Gentle ROM exercises
   • Quadriceps activation

2. Rehabilitation Phase (2-12 weeks):

   • Progressive strengthening
   • Proprioceptive training
   • Stationary cycling
   • Aquatic therapy

3. Return to Activity:

   • Functional brace for sport
   • Avoid pivoting/cutting sports
   • Activity modification

Failure of Non-operative Treatment: Symptomatic instability (recurrent giving way) despite rehabilitation indicates need for reconstruction.

Absolute Indications for Reconstruction:

• Symptomatic instability affecting ADLs
• Combined ligament injuries requiring surgery
• Repairable meniscal tear in unstable knee (ACL reconstruction improves meniscal healing)

Strong Relative Indications:

• Young, active patient (less than 25 years)
• High-level athlete wanting return to pivoting sports
• High-demand occupation
• High-grade pivot shift
• Meniscal injury at high risk of further damage

Relative Contraindications:

• Significant osteoarthritis
• Limited ROM (not yet restored)
• Active infection
• Unrealistic patient expectations

Timing: Optimal timing is 4-8 weeks post-injury with full ROM restored and minimal effusion.

Procedures Commonly Combined with ACL Reconstruction:

1. Meniscal Surgery (40-60% of cases):

   • Meniscal repair preferred over meniscectomy
   • ACL reconstruction improves meniscal healing rates
   • Address at time of ACL reconstruction

2. Collateral Ligament Management:

   • Isolated MCL: Non-operative treatment, stage ACL reconstruction
   • LCL/posterolateral corner: May require reconstruction

3. Lateral Extra-articular Tenodesis (LET):

   • STABILITY study: 87% reduction in graft rupture
   • Consider in high-risk patients: young, high-grade pivot shift, returning to pivoting sport
   • Modified Lemaire or iliotibial band tenodesis

4. Chondral Procedures:

   • Debridement of unstable fragments
   • Microfracture or osteochondral grafting if indicated

Goal: Anatomic position in center of native femoral footprint.

Landmarks:

• Resident's ridge: Bony ridge marking anterior edge of footprint
• Posterior to resident's ridge
• Center of combined AM/PL footprint (single bundle)

Technique Options:

• Transportal: Drill through AM portal with knee hyperflexed. Better anatomic position.
• Transtibial: Drill through tibial tunnel. Historical technique, may limit anatomic positioning.
• Outside-in: Drill from lateral femoral cortex. Allows independent positioning.

Clock Position: 10 o'clock (right knee) or 2 o'clock (left knee) for single bundle. Avoid too vertical.

Goal: Anatomic position in center of native tibial footprint.

Landmarks:

• Posterior to anterior horn of lateral meniscus
• Lateral to medial tibial spine
• Behind intersection of ACL stump remnant and lateral meniscus

Errors:

• Too anterior: Roof impingement in extension. Most common error. Causes graft failure.
• Too posterior: Less common but affects stability.

Technique: Use tibial guide (usually 55-65 degrees). Start point on anteromedial tibia. Confirm position arthroscopically.

Graft Preparation: Size to match tunnels. BTB: Bone plugs sized. Hamstring: Whipstitch ends, size diameter.

Passage: Pass graft through tibial tunnel, into joint, then into femoral tunnel.

Fixation:

• Femoral: Suspensory (EndoButton, TightRope), interference screw, cross-pin
• Tibial: Interference screw, post fixation, staple
• Tensioning: At 15-20 degrees flexion. Apply tension while cycling knee.

Proper tensioning and fixation are critical for graft function and longevity.

Intraoperative Complications:

Early Post-operative (0-6 weeks):

• Haemarthrosis: Common, manage with aspiration if tense
• Infection: 0.5-1% incidence, aggressive treatment required
• DVT/PE: Thromboprophylaxis, early mobilization
• Nerve injury: Saphenous nerve (hamstring harvest), peroneal nerve (positioning)

Late Complications:

Cyclops Lesion:

• Fibrous nodule anterior to graft
• Causes mechanical block to extension
• Arthroscopic excision with good outcomes

BTB Graft Complications:

• Anterior knee pain: 10-20%
• Kneeling pain: 15-30%
• Patellar fracture: less than 1%
• Patellar tendon rupture: Rare
• Patellofemoral crepitus

Hamstring Graft Complications:

• Hamstring weakness: Variable
• Tunnel widening: More common than BTB
• Saphenous nerve injury: During harvest
• Graft too small: less than 8mm associated with failure

Allograft Complications:

• Higher failure rate in young athletes
• Disease transmission (rare with modern processing)
• Slower incorporation

Phase 1: Protection Phase (0-2 weeks)

Goals:

• Protect graft
• Control pain and swelling
• Restore full extension
• Achieve 90° flexion

Weight-Bearing:

• Partial weight-bearing with crutches
• Weight-bearing as tolerated by 2 weeks (graft dependent)

Exercises:

• Quadriceps setting (isometrics)
• Straight leg raises (when quad control achieved)
• Ankle pumps, heel slides
• Passive extension to 0° (critical)
• Patellar mobilization

Modalities:

• Ice, elevation
• Compression
• Gentle ROM exercises

Phase 2: Early Rehabilitation (2-6 weeks)

Goals:

• Full ROM (0-130°)
• Normal gait pattern
• Progressive strengthening

Weight-Bearing:

• Full weight-bearing without crutches by 4-6 weeks
• Normal gait pattern

Exercises:

• Closed kinetic chain exercises (mini squats, leg press)
• Stationary cycling
• Pool exercises
• Progressive ROM exercises
• Core strengthening

Restrictions:

• No open chain extension exercises (0-45°)
• No running or jumping
• Brace optional (surgeon preference)

Phase 3: Strengthening Phase (6-12 weeks)

Goals:

• Strength 70% of contralateral
• Single leg balance
• Begin sport-specific training

Activities:

• Increased resistance training
• Balance and proprioception
• Light jogging (after 12 weeks)
• Sport-specific drills (non-contact)

Phase 4: Return to Sport (4-9 months)

Criteria for Sport Return:

• Isokinetic strength greater than 85% of contralateral
• Single-leg hop test greater than 85%
• No pain or effusion
• Psychological readiness
• Passed functional testing battery

Timeline:

• Non-contact training: 4-6 months
• Full contact practice: 6-9 months
• Competition: 9-12 months (depends on sport level)

Overall Success Rates:

Functional Outcome Scores:

• IKDC subjective score: Improvement from 50 to 85+
• Lysholm score: Improvement to 85-90+
• Tegner activity scale: Often 1-2 levels below pre-injury

Long-term Considerations:

• 50-70% develop radiographic OA by 15-20 years
• Symptomatic OA less common
• Meniscal injury at time of ACL injury is major risk factor for OA

Graft-Specific Outcomes:

Evidence Summary:

• Meta-analyses show similar overall outcomes
• BTB may have slight advantage in stability
• Hamstring has lower donor site morbidity
• Graft diameter more important than graft type

Risk Factors for Poor Outcome:

Patient Factors:

• Young age (less than 20 years): Higher re-rupture risk
• Female sex: Higher re-rupture in some studies
• High-level pivoting sport return
• Delayed rehabilitation

Surgical Factors:

• Graft diameter less than 8mm
• Non-anatomic tunnel placement
• Inadequate fixation
• Unaddressed associated injuries

Revision ACL Reconstruction:

• Success rate 75-85% (lower than primary)
• Higher failure rate in revision of revision
• Often requires staged procedures
• Consider lateral tenodesis augmentation

ACL Injury in Australia:

• Incidence: Approximately 17,000 ACL reconstructions performed annually
• Peak age group: 15-25 years
• Sex distribution: Males have higher absolute numbers; females have 2-3x higher rate in same sports
• High-risk sports: AFL, netball, soccer, rugby, skiing

Australian Football League (AFL):

• ACL injury rate: 0.8 per club per season
• Major cause of games missed
• Significant media and research attention

Netball:

• One of highest ACL injury rates in female sport
• Knee Injury Prevention Program (KIPP) widely promoted

Public System Coverage:

ACL reconstruction and associated procedures are covered under the Australian public hospital system. Surgical procedures including primary and revision ACL reconstruction, combined ligament reconstructions, diagnostic arthroscopy, and meniscal surgery are fully funded.

Note: Wait times vary by state. Private insurance covers procedures with potential gap fees.

Private Health Insurance:

• Most policies cover ACL reconstruction
• Excess and gap payments apply
• Pre-existing condition exclusions may apply for some patients

Australian Guidelines and Resources:

AOSSM/ESSKA/ISAKOS Consensus:

• Anatomic reconstruction recommended
• Graft choice based on patient factors
• Minimum 8mm graft diameter

Australian Knee Society:

• Rehabilitation protocols
• Return to sport criteria
• Registry data contribution

State Sporting Organizations:

• ACL injury prevention programs
• Injury surveillance systems
• Return to play protocols

Research Contribution:

• MARS (Multicenter ACL Revision Study) - Australian centers contributing
• STABILITY Study (lateral tenodesis) - significant Australian authorship
• La Trobe Sport and Exercise Medicine Research Centre