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

Rehabilitation Protocol After MCL Repair During Total Knee Replacement

MCL repair during TKR requires a significantly more conservative and protective rehabilitation approach than isolated TKR, with delayed weight-bearing, restricted range of motion initially, and extended protection phases to allow ligament healing—fundamentally different from standard rapid recovery TKR protocols.

Critical Distinction from Standard TKR Rehabilitation

The presence of MCL repair fundamentally changes the rehabilitation timeline and approach. While modern TKR rehabilitation emphasizes immediate weight-bearing and rapid mobilization 1, 2, MCL repair requires absolute control of forces during early healing to prevent disruption of the repair site 3.

Standard rapid recovery TKR protocols that include same-day mobilization and immediate weight-bearing 1 are contraindicated when MCL repair is performed concurrently. The ligament healing requirements take precedence over joint mobilization goals 3.

Phase 1: Maximum Protection (0-6 Weeks)

Early Healing Period (Weeks 0-2)

• Knee immobilization in a hinged brace locked in extension or 0-20° flexion is required to protect the MCL repair site during the critical early healing phase 3
• Non-weight-bearing or touch-down weight-bearing only (20-30 lbs maximum) with crutches to prevent valgus stress on the MCL repair 3
• Passive range of motion limited to 0-30° initially, progressing cautiously based on surgical technique and repair tension 3
• Isometric quadriceps exercises in protected positions only (avoiding valgus stress), including quad sets and straight leg raises with brace locked 3, 4
• Cryotherapy application for pain and swelling control during the first postoperative week 5, 6

Controlled Motion Period (Weeks 3-6)

• Gradual ROM progression to 0-60° by week 4 and 0-90° by week 6, but only if MCL stability is maintained on examination 3
• Partial weight-bearing (50% body weight) may begin at week 4-6 if adequate quadriceps control and no valgus instability 3
• Continue hinged brace use during all ambulation and exercises 3
• Closed kinetic chain exercises in protected ranges only (avoiding terminal extension initially) 6, 4
• Neuromuscular electrical stimulation should be used for quadriceps activation to prevent atrophy while mechanical loading is restricted 6

Phase 2: Moderate Protection (Weeks 6-12)

Crutch Weaning Period (Weeks 6-10)

• Progress to full weight-bearing only when quadriceps strength reaches 60-70% of contralateral limb and no effusion or valgus laxity is present 3, 4
• Continue hinged brace during ambulation, unlocked for controlled motion 3
• Achieve full passive extension (0°) and flexion to 110-120° by week 10 3, 2
• Low-resistance closed kinetic chain exercises through protected ranges (30-90° flexion) 3, 4
• De-emphasize quadriceps-dominant exercises and emphasize hamstring strengthening to avoid excessive anterior tibial translation and valgus stress 3

Walking Period (Weeks 10-12)

• Full weight-bearing without assistive devices by week 12 if strength and stability criteria met 3
• Discontinue brace for indoor activities if valgus stability confirmed clinically 3
• Progress to full ROM exercises (0-130° flexion goal) 2
• Stationary cycling and aquatic therapy may be initiated once wound fully healed (typically week 8-10) 5, 6

Phase 3: Minimum Protection (Weeks 12-24)

Protected Activity Period (Weeks 12-18)

• Continue brace use for outdoor activities and uneven terrain through week 16-18 3
• Progressive resistance training with emphasis on balanced quadriceps-hamstring strengthening 3, 2
• Core stability exercises to improve gait mechanics and functional outcomes 5
• No running, jumping, or pivoting activities during this phase 3
• Quantitative rehabilitation training with specific functional milestones (6-minute walk test, stair climbing) 2

Light Activity Period (Weeks 18-24)

• Discontinue brace if full strength and stability achieved 3
• Advanced closed and open kinetic chain exercises 3, 4
• Achieve limb symmetry index (LSI) >80% for quadriceps strength before progressing 7
• Proprioceptive and balance training 5

Phase 4: Return to Activity (Months 6-12)

Advanced Rehabilitation (Months 6-9)

• Plyometric and agility training may be introduced cautiously once LSI >85% for strength and no valgus instability 5
• Sport-specific training if applicable, with gradual progression 7
• Minimum 9 months before considering return to high-demand activities (significantly longer than isolated TKR) 3

Return to Full Activity (Months 9-12)

• Achieve LSI >90% for strength testing and functional hop tests before unrestricted activity clearance 7, 6
• Full ROM without pain or effusion required 7, 2
• Clinical examination confirming MCL stability (no grade 2 or 3 laxity) 3

Critical Differences from Isolated TKR

• Standard TKR allows immediate weight-bearing and same-day mobilization 1, 4, while MCL repair requires 6-12 weeks of protected weight-bearing 3
• Isolated TKR targets full ROM by 2-3 weeks 2, 8, while MCL repair limits ROM to 60° at 4 weeks and 90° at 6 weeks 3
• TKR patients typically discharge to home exercise programs 8, while MCL repair requires supervised therapy to monitor valgus stability 3
• Return to activities occurs at 6-8 weeks for TKR 4, 8, but requires 6-12 months with concurrent MCL repair 3

Common Pitfalls to Avoid

• Applying rapid recovery TKR protocols when MCL repair is present will cause ligament failure and require revision surgery 3, 1
• Advancing weight-bearing before adequate quadriceps control creates valgus stress and repair disruption 3
• Aggressive ROM exercises in the first 6 weeks can stretch or rupture the healing MCL 3
• Premature discontinuation of brace protection before clinical stability is confirmed 3
• Neglecting hamstring strengthening in favor of quadriceps-dominant exercises creates muscle imbalance and abnormal knee kinematics 3