What is the recommended rehabilitation approach after Total Knee Replacement (TKR) with Medial Collateral Ligament (MCL) repair?

Rehabilitation After Total Knee Replacement with MCL Repair

After TKR with MCL repair, initiate immediate knee mobilization within the first week while prioritizing closed kinetic chain exercises over open kinetic chain exercises during the first 6-8 weeks to protect the healing MCL, then progress through criterion-based phases combining strength and motor control training over 3-6 months. 1

Immediate Postoperative Phase (0-2 Weeks)

Begin knee mobilization within the first week to improve range of motion and reduce pain without compromising stability—this is critical to prevent stiffness while respecting the MCL repair. 1

Weight-Bearing Protocol

• Progress weight-bearing as tolerated within the first week, though more conservatively than isolated ACL reconstruction given the MCL repair. 1
• Early weight-bearing reduces patellofemoral pain without increasing laxity, but only if correct gait pattern is maintained without pain, effusion, or temperature increase. 1
• Use crutches if necessary to maintain proper mechanics. 1

Early Exercise Prescription

• Start isometric quadriceps exercises during the first 2 postoperative weeks, including static quadriceps contractions and straight leg raises—these safely accelerate recovery of knee range of motion at 1 month without compromising stability. 1
• Apply cryotherapy immediately after surgery to reduce knee pain and swelling. 1
• Consider neuromuscular electrostimulation (NMES) for the initial 6-8 weeks to re-educate voluntary quadriceps contraction. 1

Critical Early Phase Pitfall

Do not use postoperative knee immobilizers—they provide no additional benefit and impede rehabilitation progress. 2

Moderate Protection Phase (2-6 Weeks)

Prioritize closed kinetic chain exercises (leg press, squats, step-ups) over open kinetic chain exercises to minimize stress on the MCL repair during this critical healing window. 1

Exercise Progression

• Closed kinetic chain exercises should be emphasized in the first 6-8 weeks to protect the healing ligament. 1
• Begin leg press at 3 weeks to improve subjective knee function and functional outcomes. 1
• Open kinetic chain exercises (90-45°) may be cautiously added as early as 4 weeks, but introduce with extreme caution given the MCL repair—avoid aggressive resistance during this phase. 1

Neuromuscular Training

Combine strength training with neuromuscular/motor control training from this phase forward—one cannot replace the other. 1

Minimum Protection Phase (6-12 Weeks)

Advance to both open and closed kinetic chain exercises with progressive resistance once the MCL has achieved sufficient healing strength. 1

Training Components

• Implement eccentric training components, which may result in greater strength gains and quadriceps muscle hypertrophy. 1
• Continue combining strength training with neuromuscular/motor control training to restore dynamic stability. 1
• Progress from basic activities of daily living to more demanding functional tasks. 1

Return to Function Phase (3-6 Months)

Base progression on objective criteria rather than time alone—time is necessary but not sufficient for advancement. 1

Objective Criteria for Clearance

• Achieve limb symmetry index >90% for strength testing before advancing to higher-level activities. 1
• Ensure no pain, swelling, or instability on examination. 1
• Perform isokinetic quadriceps and hamstring peak torque testing at 60°/s demonstrating 100% symmetry. 1
• Assess countermovement jump and drop jump with >90% symmetry. 1
• Evaluate patient-reported outcomes including IKDC subjective knee form and psychological readiness scales. 1

Key Algorithmic Decision Points

When to Advance from Closed to Open Kinetic Chain Exercises

• Before 4 weeks: Closed kinetic chain exercises ONLY. 1
• 4-6 weeks: Cautiously introduce open kinetic chain (90-45°) with minimal resistance. 1
• After 6 weeks: Progress both open and closed kinetic chain exercises with increasing resistance. 1

When to Progress Weight-Bearing

• Week 1: Weight-bearing as tolerated with assistive devices if needed to maintain proper gait mechanics. 1
• Weeks 2-6: Progressive weight-bearing based on absence of pain, effusion, and temperature increase. 1
• After 6 weeks: Full weight-bearing without restrictions if criteria met. 1

Critical Pitfalls to Avoid

• Do not advance to aggressive open kinetic chain exercises before 4 weeks—this risks disrupting the MCL repair. 1
• Do not rely on time-based progression alone—use objective functional measures and clinical examination findings. 1
• Do not neglect motor control training—strength training alone is insufficient for optimal outcomes. 1
• Do not use continuous passive motion—it provides no additional benefit compared to active motion exercises and wastes time and resources. 2