What is the rehabilitation protocol after a lateral collateral ligament (LCL) avulsion injury of the knee?

Rehabilitation Protocol After LCL Avulsion Injury of the Knee

For isolated, minimally displaced LCL femoral avulsion fractures with intact superior lateral genicular artery, articular capsule, and IT band, conservative treatment with protected weight-bearing and progressive range of motion is recommended, with most patients achieving full recovery by 10 weeks. 1

Initial Assessment and Treatment Decision

The rehabilitation approach depends critically on the specific characteristics of the LCL avulsion:

• Femoral avulsion fractures that are minimally displaced and noncomminuted, with preserved integrity of the superior lateral genicular artery, adjacent articular capsule, and IT band can be managed conservatively 1
• Distal (fibular) avulsion injuries are more common and may require surgical fixation, particularly if displaced 1
• Complete radiographic evaluation including X-rays, MRI, and CT scan is essential to confirm no other associated knee lesions and assess displacement 1

Conservative Management Protocol (For Appropriate Candidates)

Phase 1: Maximum Protection (Weeks 0-6)

• Immediate immobilization with knee brace or immobilizer to prevent secondary displacement 1
• Protected weight-bearing as tolerated with crutches, avoiding varus stress 1
• Early gentle range of motion within pain-free limits to prevent stiffness, while avoiding positions that stress the LCL 1
• Isometric quadriceps exercises including static quadriceps contractions can be safely prescribed during the first 2 postoperative weeks 2
• Cryotherapy to reduce pain and swelling 3

Phase 2: Moderate Protection (Weeks 6-10)

• Progressive weight-bearing advancement as fracture healing progresses 1
• Gradual increase in range of motion exercises 1
• Closed kinetic chain exercises should be prioritized over open kinetic chain exercises during this phase 2, 3
• Hamstring strengthening is particularly important given the LCL's role in posterolateral stability 4
• Varus stress radiographs at 20° knee flexion should be performed to confirm no side-to-side differences and assess healing 1

Phase 3: Return to Function (Weeks 10-16)

By 10 weeks post-injury, appropriately selected patients should be asymptomatic with early radiological fracture healing evidence 1:

• Clinical examination should demonstrate no posterolateral rotatory instability 1
• Progressive strengthening with both open and closed kinetic chain exercises 2
• Neuromuscular training to restore dynamic stability 2
• Functional progression based on achieving specific milestones rather than time alone 2

Surgical Management Rehabilitation (For Displaced or Unstable Injuries)

When anatomic repair with internal brace augmentation is performed 5:

• Early range of motion and weight-bearing can be facilitated due to the augmented repair construct 5
• Full return to sports typically occurs at 9 months postoperatively 5
• Excellent outcomes regarding stability, ROM (135° achieved), and return to preoperative sports are expected 5
• Progressive strengthening protocol similar to ACL reconstruction guidelines, with emphasis on posterolateral corner stability 2

Critical Rehabilitation Principles

Weight-Bearing Progression

• Immediate full weight-bearing should NOT be used in acute LCL avulsion injuries, unlike ACL reconstruction protocols 1
• Protected weight-bearing with gradual advancement based on fracture healing is essential 1
• Varus stress must be avoided during the healing phase 1

Exercise Selection

• Closed kinetic chain exercises (leg press, squats, step-ups) should be prioritized in the first 6-8 weeks 2, 3
• Open kinetic chain exercises (90-45°) can be added as early as 4 weeks but should be introduced cautiously 2
• Hamstring and quadriceps strengthening should be balanced, with particular attention to posterolateral stability 4

Monitoring and Progression Criteria

• Serial imaging to confirm fracture healing before advancing activities 1
• Comparative varus stress testing to ensure no increased laxity 1
• Clinical examination for posterolateral rotatory instability at each progression point 1
• Functional testing including single-leg balance and hop tests before return to sport 2

Common Pitfalls to Avoid

• Applying ACL reconstruction protocols directly to LCL injuries—these are fundamentally different injuries requiring different protection strategies 1
• Early aggressive weight-bearing in minimally displaced fractures can lead to secondary displacement 1
• Neglecting posterolateral corner assessment—isolated LCL injuries are rare, and associated injuries must be ruled out 1, 5
• Premature return to varus-loading activities (cutting, pivoting) before adequate healing and strength restoration 1
• Relying solely on time-based criteria rather than objective functional measures for progression 2

Return to Sport Considerations

• Minimum 12-16 weeks for isolated, conservatively managed LCL avulsion fractures with confirmed healing 1
• Minimum 9 months for surgically repaired injuries 5
• Limb symmetry index >90% for strength testing before sport clearance 2
• No posterolateral rotatory instability on clinical examination 1
• Sport-specific functional testing demonstrating readiness 2