Injury to the PCL most commonly results from direct impact to the proximal aspect of the tibia such as a fall directly onto a bent knee or hitting the glove compartment in an automobile accident. This can occur as an isolated ligament injury, such as with direct blows or with combined instability as would occur in a twisting injury.
 

An accurate diagnosis and early intervention is essential in order to optimize outcome. After obtaining a careful history, the following special tests aid in determining which structures are involved:

Posterior drawer test - With the knee in 90º of flexion, look for a 'sag' of the tibia on the femur.

Posterior Lachman's test - With the knee in 30º of flexion, the examiner pushes posteriorly on the tibia while holding the femur.

Posterior-lateral rotary laxity - Valgus stress testing and internally and externally rotating the ankles with the knee in flexion while looking for increases in rotation.

Reverse pivot shift - The examiner puts a valgus (medial) force on the knee while externally rotating and extending the knee, looking for the tibia to 'shift.'

It is important to take a careful history for the mechanism of the injury and to perform the tests carefully since PCL ruptures can mimic that of an ACL. An MRI aids in confirming the diagnosis and identifying associated pathology.

It has been well documented that injury to the PCL left untreated will lead to eventual medial and subsequent patellofemoral osteoarthritic changes. Therefore, we usually choose to reconstruct complete tears of the PCL, as well as any other structures associated with the instability. Proximal tears of the PCL that detach from the bone can be repaired by reattaching the ligament back to its origin. Mid-substance tears require reconstruction in active people.