The posterior cruciate ligament (PCL) is the largest and strongest ligament in the knee. PCL injuries are less common than ACL injuries and are often missed because their symptoms can be subtle. Most isolated PCL injuries are treated non-surgically, but specific high-grade injuries and those combined with other ligament injuries require surgical reconstruction.
What Is a PCL Injury?
The PCL runs from the posterior aspect of the tibia to the medial femoral condyle inside the knee, forming an X-shape with the ACL. It is the primary restraint against posterior translation of the tibia relative to the femur and provides secondary restraint against external rotation at higher flexion angles.
PCL injuries are graded based on the degree of posterior tibial displacement compared to the femur:
- Grade I: less than 5 mm posterior translation (partial tear)
- Grade II: 5 to 10 mm posterior translation (partial to complete tear)
- Grade III: more than 10 mm posterior translation (complete tear, often with associated posterolateral corner injury)
Isolated PCL injuries often heal with non-surgical treatment because the PCL has a blood supply and the knee’s natural posture keeps the ligament ends in apposition. Combined PCL and posterolateral corner injuries do not heal reliably and typically require surgical reconstruction.
Causes and Risk Factors
- Dashboard injury: direct impact to the front of the tibia driving it posteriorly, common in motor vehicle collisions
- Fall onto a flexed knee with the foot plantarflexed (rolling over the top of the foot)
- Hyperextension injuries with associated anterior knee contact
- Sports mechanisms including football, rugby, and skiing
- Hyperflexion injuries of the knee
Symptoms
- Posterior knee pain after the injury
- Swelling that is often less dramatic than ACL swelling
- Difficulty descending stairs or slopes
- Vague instability rather than a clear giving-way
- Pain with kneeling or prolonged sitting in some cases
- Many PCL injuries are missed because the symptoms are less dramatic than ACL injuries
Diagnosis
Dr. Chudik’s evaluation includes the mechanism of injury and a physical examination with specific PCL testing. The posterior drawer test is the most sensitive, assessing posterior tibial translation with the knee in 90 degrees of flexion. The posterior sag sign and quadriceps active test add specificity. Associated testing for the posterolateral corner is always performed because isolated PCL injury is less common than combined PCL and PLC injury. X-rays rule out associated avulsion fractures. MRI confirms the tear and characterizes associated injuries. The Westmont office has on-site high-field MRI and X-ray.
Treatment
Non-surgical treatment is appropriate for isolated grade I and grade II PCL injuries. It involves:
- A hinged knee brace for several weeks
- Protected weight-bearing initially, progressing as tolerated
- A targeted physical therapy program focused on quadriceps strengthening (quadriceps are critical PCL agonists)
- Avoidance of resisted hamstring work during early healing (hamstrings pull the tibia posteriorly and stress the PCL)
- Gradual return to activity over 8 to 12 weeks
Surgical reconstruction is indicated for grade III isolated PCL injuries in active patients, for combined PCL and posterolateral corner injuries, for multi-ligament knee injuries, and for failed non-surgical treatment with persistent instability. Dr. Chudik performs arthroscopic PCL reconstruction, often using a tunnelless technique he has developed that avoids drilling a large bone tunnel across the tibia, reducing the risk of neurovascular injury and preserving bone stock.
Recovery and Outcomes
Recovery after isolated non-surgical treatment typically allows return to sport in 8 to 12 weeks depending on grade. Recovery after PCL reconstruction is longer, typically including six weeks of brace protection, progressive motion over three months, and return to sport at six to nine months. Combined reconstructions have longer recoveries pending full ligament healing and strength restoration.
Outcomes for isolated PCL injuries treated non-surgically are generally good. Outcomes after reconstruction are more variable than ACL reconstruction, which reflects the complexity of PCL biomechanics and the common presence of associated injuries.
When to See Dr. Chudik
Schedule an evaluation after any knee injury involving a dashboard mechanism or a fall on a flexed knee, if you have vague posterior knee instability, or if prior treatment has not resolved symptoms. Call 630-324-0402 or request an appointment online.