What are the details of ACL (Anterior Cruciate Ligament) reconstruction surgery, including preoperative evaluation, surgical techniques, and postoperative rehabilitation for a patient undergoing this procedure?

ACL Reconstruction Surgery: Anatomical and Technical Details

Anatomical Considerations

The ACL femoral footprint centrum is located at 43% of the proximal-to-distal length of the lateral femoral intercondylar notch wall, with the femoral socket positioned 2.5 mm anterior to the posterior articular margin. 1

Key Anatomical Landmarks for Tunnel Placement

• The medial tibial eminence and intermeniscal ligament serve as critical landmarks for correct tibial tunnel placement in anatomic ACL reconstruction 1
• Separate femoral tunnel placement (independent drilling) produces superior outcomes compared to transtibial approach 1
• The ACL consists of two functional bundles (anteromedial and posterolateral) that must be considered during reconstruction planning 1

Preoperative Evaluation and Preparation

Essential Preoperative Assessment

• Measure preoperative knee range of motion, particularly extension deficit, as full extension reduces risk of postoperative arthrofibrosis 2
• Assess quadriceps strength bilaterally; a preoperative deficit >20% predicts significant strength deficits persisting 2 years post-surgery 2
• Evaluate hamstring strength despite limited evidence mandating this measurement 2
• Confirm adequate voluntary quadriceps activation and absence of flexion contracture 2

Preoperative Rehabilitation (Prehabilitation)

• Implement 3-6 weeks of preoperative rehabilitation to improve postoperative quadriceps strength at 3 months and potentially decrease time to return to sport 2
• Preoperative rehabilitation improves knee flexion and extension in the early postoperative phase 2
• Progressive preoperative and postoperative rehabilitation programs result in superior patient-reported outcomes both preoperatively and 2 years postoperatively compared to usual care 3
• Educate patients preoperatively about crutch walking, early postoperative exercises, and the rehabilitation timeline 2

Surgical Technique Considerations

Graft Selection and Fixation

• Critical factors affecting surgical outcome include graft selection, tunnel placement, initial graft tension, graft fixation, graft-tunnel motion, and healing 1
• Both bone-patellar tendon-bone (BTB) and hamstring autografts are viable options with specific rehabilitation considerations 2

Tunnel Placement Principles

• Non-anatomic tunnel placement is one of the most frequent causes of graft failure 4
• Anatomic tunnel positioning is essential for replicating natural ACL biomechanics and preventing future pathology 1

Postoperative Rehabilitation Protocol

Immediate Postoperative Phase (0-1 week)

• Do not use postoperative knee braces routinely, as they provide no benefit and impede rehabilitation progress 2, 5
• Initiate immediate full weight-bearing as tolerated within the first week 2, 5
• Begin isometric quadriceps weight-bearing and non-weight-bearing concentric/eccentric exercises from the first postoperative week 2, 5
• Apply cryotherapy immediately postoperatively to reduce pain and swelling 2, 5
• Compressive cryotherapy may be more effective than standard cryotherapy alone 2, 5

Early Phase (1-8 weeks)

• Prioritize closed kinetic chain exercises (leg press, squats, step-ups) over open kinetic chain exercises during weeks 1-8 2, 6, 5
• Open kinetic chain exercises (90-45°) may be introduced as early as 4 weeks but should be used cautiously 2, 6
• Use neuromuscular electrical stimulation for the initial 6-8 postoperative weeks to improve quadriceps activation and strength 2, 5
• Continuous passive motion provides no additional benefit compared to active motion exercises and is not recommended 5

Intermediate Phase (2-4 months)

• Combine strength training with neuromuscular training throughout rehabilitation 2
• Implement neuromuscular re-education training in addition to muscle strengthening exercises 2
• Low-load blood flow restriction training may improve quadriceps and hamstring strength and prevent disuse atrophy during early phases 2

Advanced Phase (>4 months)

• Consider return to running at approximately 12 weeks using a combination of time-based, clinical, and functional criteria 5
• Introduce plyometric and agility training to improve subjective function and functional activities 5

Rehabilitation Duration and Progression

The duration of rehabilitation is individualized and criteria-based rather than time-based, with accelerated timelines possible under appropriate conditions while respecting minimum time requirements for graft protection and healing. 2, 5

• A 19-week rehabilitation protocol shows no differences in knee laxity or other outcomes compared to longer duration protocols 2
• Progression should be based on achieving specific functional milestones rather than time alone 6

Supervised vs. Unsupervised Rehabilitation

• Unsupervised (home-based) rehabilitation may be appropriate for highly motivated, compliant patients with limited access to physical therapy 2, 5
• Programs must be individually prescribed and monitored for proper execution and progression without adverse events 2, 5
• There is no significant difference between supervised and unsupervised rehabilitation when programs are properly designed 2

Return to Sport Criteria

Functional Testing Requirements

• Use an extensive test battery combining validated patient-reported outcome measures (IKDC 2000 or KOOS), activity level tools (Tegner or Marx), and psychological questionnaires (ACL-RSI) 2
• Implement functional performance assessment using appropriate clinical or field testing 2
• Achieve limb symmetry index (LSI) >90% for strength and hop tests before sport clearance 2, 6
• For pivoting/contact sports, target LSI ≥100% 2

Timing Considerations

• Minimum 3-month cut-off before resuming heavy physical activity or sports 2
• The rate of return to preinjury play level for non-professional pivoting athletes is 65% 2
• Only 38% of athletes remain at preinjury competitive level >2 years after ACLR 2
• Minimum 9-12 months should be considered before return to sport decisions 7

Psychological Factors

• High self-efficacy, high internal locus of control, and low fear levels are associated with higher return-to-play rates 2
• Assess psychological readiness using validated instruments as part of return-to-sport criteria 2

Common Pitfalls and How to Avoid Them

• Avoid relying solely on time-based criteria for progression; always use objective functional measures 5
• Do not use kinesio-taping, as it has minimal to no therapeutic effect despite low cost 5
• Ensure communication between surgeon and physical therapist regarding perioperative findings, graft type, and any meniscal procedures 2
• Recognize that preoperative extension deficits are major risk factors for postoperative extension deficits and arthrofibrosis 2
• Address modifiable risk factors and concomitant injuries during preoperative planning to reduce revision risk 8

Revision Surgery Considerations

• The most frequent causes of graft failure are traumatic events, non-anatomic tunnel placement, and lack of graft incorporation 4
• Revision ACLR requires more conservative progression with extended protection phases before aggressive strengthening 7
• Delaying revision surgery beyond 3 months significantly increases risk of irreversible meniscal and cartilage damage 7
• Revision surgery has high rates of excellent and good outcomes (85.7% optimal, 7.2% good results) when properly executed 4