What is the appropriate management for posterior cruciate ligament (PCL) injuries?

Management of Posterior Cruciate Ligament (PCL) Injuries

Key Clinical Truths About PCL Injuries

Most isolated PCL injuries should be managed non-operatively with intensive quadriceps rehabilitation, as functional outcomes depend more on muscle strength than residual laxity, and surgery has historically shown only modest success in restoring complete stability. 1, 2, 3

Anatomical and Biomechanical Considerations

• The PCL is the strongest knee ligament, approximately twice as strong as the ACL, providing 95% of resistance to posterior tibial displacement 2
• The ligament consists of two codominant bundles (anterolateral and posteromedial) that work synergistically with meniscofemoral ligaments 4, 5
• PCL injury occurs in more than one-third of acute knee trauma patients with hemarthrosis, making background knowledge essential 4

Diagnostic Approach

MRI is the gold standard for diagnosis, achieving 96% sensitivity and 97% specificity on 3T equipment 6, 7

Key clinical findings include:

• Posterior sag sign: disappearance of tibial tubercle on lateral inspection at 90° flexion due to gravity-assisted posterior tibial displacement 2
• Positive posterior drawer test at 90° flexion (sensitive but nonspecific) 2
• Knee hyperextension sign 2

Important caveat: False negative findings are frequent in acute cases, so examination under anesthesia or arthroscopy may be necessary 2

Treatment Decision Algorithm

Isolated PCL Injuries

Grade I-II (partial tears):

• Non-operative management is strongly recommended 1, 2, 3
• Intensive quadriceps strengthening exercises are the cornerstone of treatment 2
• Short immobilization period (under 2 weeks) followed by early controlled activities and weightbearing 2

Grade III (complete midsubstance tears):

• Conservative treatment remains the initial approach for most isolated complete tears, as abnormal residual posterior laxity is often consistent with functional stability and minimal symptoms, even in athletes 1, 2
• However, early surgical reconstruction should be considered for Grade III injuries based on emerging evidence showing correlation between injury duration and degenerative changes 1
• Surgical outcomes show 77.4% satisfactory results at medium-term follow-up, though complete stability restoration occurs in only 52% of cases 1

PCL avulsion fractures:

• Surgical treatment is recommended when an avulsion fragment has been displaced 2, 3

Combined PCL and Posterolateral Corner Injuries

There is clear consensus that surgical reconstruction is indicated for combined PCL and posterolateral instabilities, as these are serious injuries frequently resulting in severe functional disability from pain, instability, and degenerative changes 1, 3

Surgical approach includes:

• Combined arthroscopic PCL reconstruction with posterolateral reconstruction (popliteus reconstruction, lateral collateral ligament reconstruction/advancement, or combination) 1
• Outcomes show 64% satisfactory results (24% excellent, 40% good) with complete stability restoration in only 44% of knees 1
• Critical timing factor: Early surgical reconstruction achieves the best clinical results and highest patient satisfaction 1

Combined PCL and MCL Injuries

• Non-surgical treatment of the MCL component results in good outcomes 6, 7
• Surgical treatment of the MCL may be considered in select cases 6, 7

Surgical Technique Considerations

When surgery is indicated:

• Single-bundle arthroscopic PCL reconstruction is the most commonly studied approach 1
• Both transtibial and tibial inlay techniques are used, though high-quality comparative studies are lacking 5
• Double-bundle versus single-bundle reconstruction requires further evidence level 1-2 studies 5

Prognostic Factors

Key predictors of poor outcomes:

• Duration from injury to treatment correlates with degenerative changes 1
• Severity of ligament laxity correlates with osteoarthritis development 1
• Incidence of degenerative changes ranges from 44-52% depending on injury pattern 1

Functional outcomes depend primarily on quadriceps muscle status rather than amount of residual posterior laxity 2

Rehabilitation Protocol

• Intensive quadriceps exercises are fundamental 2
• Short immobilization period (under 2 weeks maximum) 2
• Early controlled activities and early weightbearing 2
• Training of strength and motor control should be combined 7

Common Pitfalls to Avoid

• Underestimating PCL injury significance: The functional disability has been historically underestimated 1
• Delayed diagnosis: High-energy trauma and accompanying injuries may complicate diagnostic accuracy, requiring systematic evaluation 4
• False negative clinical tests: Especially in acute cases, consider advanced imaging or examination under anesthesia 2
• Overlooking concomitant injuries: PCL injuries frequently occur with multiple ligamentous injuries requiring comprehensive assessment 1, 3