Comprehensive Clinical Review: ACL Injuries, Repair, Reconstruction, and Complex Scenarios

Panel Profile and Experience

• Webinar: 5th SKI Orthopedic Webinar.
• Topic: Current trends and debates in ACL management.
• Moderator: Dr. Sachin Tapasvi.
• Panelists: Dr. Dinshaw Pardiwala, Dr. Bhushan Sabnis, Dr. Vikas Khanduja, Dr. Vikas Kapoor, Dr. Raju Easwaran, Dr. Parag Sancheti, Dr. Clement Joseph, Dr. Jacob Varughese, Dr. Mukesh Laddha, and Dr. Kanchan Bhattacharya.
• Volume: Over 10,000 ACL cases treated across the panel.

Core Diagnostic and Biomechanical Principles

Clinical Knee Laxity Testing

• Anterior Drawer Test: Poor diagnostic value in acute tears. Hamstring spasms mask joint motion.
• Lachman Test: Most reliable physical exam. Accurately identifies sagittal laxity.
• Pivot Shift Test: Evaluates rotational subluxation of the lateral tibial plateau.
• Awake patients guard during the test. Best performed under anesthesia.
• A clear pivot shift in clinic indicates gross knee instability.
• Graded by translation and velocity: Grade 1 (glide), Grade 2 (clunk), Grade 3 (explosive).

Optimal Timing for MRI

• Immediate MRI (Day 0): Shows diffuse bone bruises and hemarthrosis. Often misdiagnoses lateral capsular bruising as an LCL tear.
• Ideal Window (Days 5 to 7): Inflammation subsides. Hemarthrosis highlights meniscal and cartilage tears like a contrast agent.
• Oblique sagittal views match notch anatomy. They distinguish Sherman Type 1 tears from mid-substance tears.

Biomechanical Strain and Intraoperative Testing

• Do not repeat pivot shift tests after fixing the graft.
• Cadaver studies show 5% permanent graft loosening per repeated test.
• A clinical Lachman at 3 months creates 4% graft strain. Squatting with 13 kg creates only 1.2% strain.
• Cycle the knee gently post-fixation. Verify button seating on cortical bone without manual subluxation testing.

Case 1: Acute Proximal ACL Avulsion

Patient Clinical Profile

• Demographics: 32-year-old male weekend athlete.
• Mechanism: Non-contact twisting injury playing soccer on artificial turf.
• Timeline: Evaluated at 3 weeks post-injury after initial rehab.
• Physical Exam: ROM 2° to 135°, Grade 2 Lachman, Grade 1 pivot shift.
• Goal: Wants to return to weekend competitive sports.
• MRI: Complete femoral-sided ACL avulsion (Sherman Type 1) with a healthy distal stump.

The 12-Week Conservative Trial (Dr. Vikas Khanduja)

• Some patients (5% to 10%) compensate without surgery.
• Prescribe 12 weeks of closed-chain gym rehab.
• Test strength objectively with dynamometry and KT-1000 data.
• Operate only if instability or pivot shift persists after 12 weeks.
• Counterpoint: Delaying 12 weeks causes stump retraction. The window for primary repair is lost.

Primary ACL Repair Selection Criteria

Surgical Technique and Evidence

• Primary Suture Repair: Pass 4 to 5 high-strength whipstitches through the tibial stump. Anchor directly to the femoral footprint using knotless anchors or buttons.
• Internal Brace Augmentation: Place ultra-high-molecular-weight tape parallel to the repair. Acts as a seatbelt to protect the collagen during early healing.
• Pediatric Advantage: Effective in young children (age 7). Avoids transphyseal bone tunnels, preventing growth plate arrest.
• 5-Year Outcomes: Dr. Bhushan Sabnis reported an 80% success rate at 5 years in UK cohorts.
• Literature Warning: Lars Engebretsen stated in Arthroscopy (Feb 2020) that routine ACL repair lacks long-term randomized trial data. It should remain limited to clinical trials.

Case 2: Partial ACL Tear and Remnant Preservation

Patient Clinical Profile

• Demographics: 26-year-old active female.
• Mechanism: Fall from a two-wheeler vehicle.
• Timeline: Evaluated at 5 weeks post-injury after 3 weeks of physical therapy.
• Physical Exam: ROM 0° to 130°, Grade 2 Lachman, Grade 1+ to 2 pivot shift.
• MRI: Over 50% of cross-sectional fibers intact. No meniscal or chondral tears.

Morphologic Classification of Incomplete Tears

• Single-Bundle Rupture: Complete tear of either the AM or PL bundle while the other remains intact.
• Partial Attenuation Tear: Peripheral fiber tearing with over 50% of central tissue intact.
• Lambda Healing: The torn ACL stump scars down to the intact PCL.
• Forms a lambda shape ($\lambda$): the notch is the apex, the PCL is one leg, and the scarred ACL is the other.
• Controls anterior translation on Lachman testing but fails to control rotational pivot shifts.

Remnant-Preserving Surgical Technique

• Rationale: Preserved native stumps retain microvessels, stem cells, and mechanoreceptors. Improves graft revascularization and joint proprioception.
• Graft Prep: Harvest only the semitendinosus. Triple or quadruple it into a 7.5 to 8.0 mm autograft, sparing the gracilis.
• Surgical Steps:
  • Make a longitudinal split in the tibial stump using a #15 blade.
  • Open the split with Metzenbaum scissors.
  • Pass the tibial guide pin directly through the stump split.
  • Retract the stump with a blunt probe during motorized drilling.
  • Pull the graft through the tunnel and seat it under the vascular stump mantle.
• Remnant Fixation Options:
  • Dr. Sachin Tapasvi closes the split edges over the graft with Vicryl to prevent cyclops lesions.
  • Dr. Parag Sancheti passes traction sutures through the stump, pulls them into the femoral tunnel, and ties them over the button.

Case 3: Chronic ACL Deficiency with Genu Recurvatum

Patient Clinical Profile

• Demographics: 41-year-old male police officer.
• Timeline: Non-contact hockey injury 11 years prior (2009).
• Symptoms: Recurrent effusions and giving-way during stairs or long walks.
• Physical Exam: Grade 3 Lachman, Grade 2 pivot shift, bilateral hyperextension of -20° (ROM: -20° to 0° to 140°).
• MRI: Chronic complete ACL tear, 20 mm bucket-handle medial meniscus tear, preserved joint cartilage.

Biomechanics and Surgical Realignment

Technical Pitfalls

• Do not tension the graft and internal brace at the same angle. The stiff tape takes all the load, causing stress shielding.
• Tension the graft at 20° to 30° flexion and the brace at 0° extension.
• Place the internal brace posterior to the graft. Anterior placement abrades the notch roof and causes cyclops lesions.

Case 4: Acute Combined ACL and Grade 3 MCL Tears

Patient Clinical Profile

• Demographics: 32-year-old male.
• Mechanism: High-velocity motor vehicle accident presenting at Day 3.
• Physical Exam: Grade 3 Lachman. Grade 3 medial opening under valgus stress at both 30° flexion and 0° full extension.
• Pathoanatomy: Complete tears of the ACL, superficial MCL, deep MCL, and POL, with a tibial-sided MCL avulsion.

Treatment Strategies and Consensus

Surgical Execution

• Do not harvest ipsilateral hamstrings. The pes anserinus is the primary dynamic medial stabilizer.
• Harvesting them removes dynamic protection from an already torn MCL complex.
• Use contralateral hamstrings, ipsilateral BTB, or quadriceps autograft instead.
• Use an open medial approach. Repair layers from deep to superficial.
• Anchor meniscotibial ligaments to seat the meniscus. Anchor the sMCL and POL to restore valgus and rotational stability.

High-Yield Clinical Takeaways

• Primary ACL Repair: Reserve for acute Sherman Type 1 avulsions within 4 weeks in young, active patients. Add an internal brace for structural protection.
• Internal Bracing Role: Works as a secondary restraint. Anchor at 0° extension and position posteriorly to prevent graft stress shielding.
• Remnant Preservation: Preserves blood vessels and nerve mechanoreceptors. Secure the stump to prevent extension loss from a cyclops lesion.
• Genu Recurvatum: Place the tibial tunnel posteriorly to clear the intercondylar roof. Tension the graft at 20° to 30° flexion, and add an extra-articular tenodesis.
• Combined Grade 3 ACL-MCL Tears: Medial opening in full extension proves complete sMCL and POL rupture. Repair between Days 5 and 10, and never harvest ipsilateral medial hamstrings.