Posterior Cruciate Ligament (PCL) Injury
What is the Anatomy and Function of the PCL?
The posterior cruciate ligament (PCL) is one of the four key stabilizing ligaments of the knee joint.
It runs from the back of the tibia (shin bone) to attach to the inside of the femur (thigh bone).
The PCL works in coordination with the ACL (anterior cruciate ligament) and serves to:
Prevent the tibia from moving backward relative to the femur
Provide stability during bending (flexion) of the knee
Assist with controlling rotation and overall joint stability, especially during deceleration, downhill walking, or descending stairs
How Does the PCL Tear?
A PCL injury often results from a direct blow to the front of the tibia while the knee is bent. Common mechanisms include:
A dashboard injury during a motor vehicle accident, when the shin strikes the dashboard
A fall directly onto a bent knee, such as in sports or skiing
Hyperflexion or hyperextension injuries during contact sports
Twisting or rotational trauma in combination with other ligament injuries
PCL tears can occur in isolation but are often part of a multi-ligament injury in high-energy trauma.
What Other Concomitant Injuries Occur with a PCL Tear?
While isolated PCL tears can occur, they are frequently associated with other soft-tissue or bony injuries, including:
Posterolateral corner (PLC) injuries – involving supporting structures on the outer and back side of the knee
Medial Collateral ligament injuries
Meniscal tears
Chondral (cartilage) damage to the femur or tibia
Bone bruising or impaction fractures from direct trauma
Neurovascular injuries in severe multi-ligament trauma
PCLs in an multi-ligament injury setting are particularly important to identify, as they often require surgical reconstruction for stability.
How Do You Diagnose a PCL Tear?
Diagnosis involves a thorough history, physical examination, and imaging studies.
Clinical Assessment:
Mechanism of injury: Direct blow to the front of the tibia or fall onto a bent knee.
Symptoms: feeling of instability—especially when walking downhill or downstairs.
Physical examination tests:
Posterior drawer test – the tibia slides backward excessively relative to the femur.
Sag sign – the tibia “drops back” when the knee is bent to 90°, compared with the uninjured side.
Quadriceps active test – the tibia moves forward when the quadriceps contract, confirming PCL insufficiency.
Imaging:
MRI scan – confirms the diagnosis of PCL injury and evaluates associated ligament, meniscal, or cartilage damage.
X-rays – may show a posterior tibial translation or avulsion fractures attached to the PCL..
What are the Long-Term Consequences of Having a PCL Injury?
A PCL injury can lead to long-term issues, including:
Chronic instability, especially when walking downhill or decelerating
Progressive cartilage wear and development of arthritis
Difficulty returning to high-demand sports requiring pivoting or sudden stops
These issues occur with conservative or surgical treatments methods.
What are the Indications for Conservative Management of PCL Tears?
Non-surgical (conservative) treatment is appropriate for many isolated or low-grade (Grade I–II) PCL injuries.
Indications include:
Partial tears or low-grade sprains
Isolated PCL tears without major instability
Low-demand patients or patients not fit for surgery
Conservative treatment typically includes:
A PCL brace to prevent posterior sag and support the knee during healing
Physiotherapy focusing on quadriceps strengthening and proprioception
Gradual return to activities over 3–6 months
Most isolated partial PCL injuries recover well with appropriate rehabilitation.
What are the indications for Surgical Management of PCL tears?
Surgical management is recommended for patients with significant instability, multi-ligament injuries, or failed conservative treatment. Indications include:
Complete PCL tears (Grade III) with persistent posterior instability
Combined injuries (e.g., PCL + PLC or collateral ligament injuries)
High-demand athletes or individuals in pivoting, cutting, or contact sports
Chronic PCL deficiency that have failed non-operative treatment
Surgery typically involves PCL reconstruction using a tendon graft to restore knee stability.
MELBOURNE ORTHOPAEDIC SURGERY