What is the recommended rehabilitation protocol after Posterior Cruciate Ligament (PCL) reconstruction surgery?

PCL Reconstruction Rehabilitation Protocol

After PCL reconstruction, implement a cautious, graft-protective protocol that restricts knee flexion to 90° until 6 weeks postoperatively, delays full weight-bearing until 6 weeks, avoids active hamstring exercises for at least 6 weeks, and uses prone passive flexion or supine ROM exercises with posterior support to prevent posteriorly directed forces on the healing graft. 1

Critical Distinction: PCL vs ACL Rehabilitation

The evidence provided is predominantly for ACL reconstruction, but PCL rehabilitation requires fundamentally different principles due to opposite biomechanical forces. PCL protocols must be significantly more conservative than ACL protocols because:

• The hamstrings create posterior tibial translation that directly stresses the PCL graft 1
• Gravity in certain positions (supine knee flexion) creates posterior sag that threatens graft healing 1
• Weight-bearing in flexion generates substantial posterior shear forces 1

Phase 1: Maximum Protection (0-6 Weeks)

Range of Motion

• Limit flexion to 90° during weeks 0-6 in 70% of published protocols 1
• Use prone passive flexion exercises OR supine passive ROM with posterior tibial support to counteract gravity-induced posterior sag 1
• Avoid positions that allow posterior tibial translation 1

Weight-Bearing

• Delay full weight-bearing until 6 weeks postoperatively (used in 60% of protocols) 1
• When weight-bearing is initiated, perform it in full extension or early flexion grades only 1
• Non-weight bearing or partial weight-bearing protects the graft during early healing 1

Bracing

• Use a brace for 6-8 weeks postoperatively (73% of protocols) 1
• The brace prevents excessive flexion and posterior tibial displacement 1

Strengthening

• Prohibit active hamstring exercises for 6-24 weeks (varies by protocol severity) 1
• Initiate quadriceps strengthening early, as quadriceps contraction creates anterior tibial translation that protects the PCL graft 1
• Implement co-contraction exercises (simultaneous quadriceps and hamstring activation) as these produce minimal posterior shear force while building strength 1

Phase 2: Moderate Protection (6-12 Weeks)

Range of Motion Progression

• Progress flexion to 120° by 6-12 weeks (70% of protocols) 1
• Continue using posterior support during passive flexion exercises 1

Weight-Bearing Advancement

• Transition to full weight-bearing after 6 weeks if soft tissue healing permits 1
• Maintain weight-bearing in extension or minimal flexion angles 1

Strengthening Progression

• Continue emphasizing quadriceps strengthening 1
• Begin gradual hamstring integration through co-contraction exercises only 1
• Avoid isolated hamstring exercises that create unopposed posterior tibial forces 1

Phase 3: Minimum Protection (12-24 Weeks)

Functional Activities

• Gradually introduce closed kinetic chain exercises, which provide better joint stability 2
• Begin considering isolated hamstring exercises only after 12 weeks minimum, with many protocols waiting until 24 weeks 1
• Monitor for posterior tibial translation during all exercises 1

Phase 4: Advanced Rehabilitation (24+ Weeks)

Return to Activity Criteria

• Do not rely solely on time-based criteria; combine with functional testing 3
• Assess quadriceps and hamstring strength symmetry 3
• Evaluate proprioception and neuromuscular control 3

Plyometric and Agility Training

• Add plyometric and agility training during advanced phases for improved subjective function and functional outcomes 4
• Plyometric training shows positive effects on knee function and psychosocial status regardless of intensity 4
• The combination of plyometric and eccentric training improves balance and functional activities 4, 3

Motor Control and Proprioception

• Integrate motor control training including unstable surface work and dynamic balance exercises to improve knee proprioception 4, 3
• Both motor control and strength training are necessary; one cannot replace the other 3

Critical Pitfalls to Avoid

• Never allow supine passive flexion without posterior tibial support - gravity creates posterior sag that stresses the graft 1
• Never initiate isolated hamstring exercises before 6 weeks minimum - this is the most common error that compromises graft healing 1
• Never progress weight-bearing in flexed positions prematurely - posterior shear forces peak in mid-flexion ranges 1
• Do not confuse ACL and PCL protocols - they require opposite protective strategies 1

Evidence Quality Note

High-quality evidence for PCL rehabilitation remains limited compared to ACL protocols 5. The systematic review by Pierce et al. (2021) found only 12 studies meeting inclusion criteria from 955 initial papers, highlighting the paucity of evidence-based PCL rehabilitation research 5. Therefore, this protocol emphasizes graft protection principles over aggressive early mobilization, contrasting sharply with modern accelerated ACL protocols 6, 7.