Copyright 2009
Definition
The posterior cruciate ligament is the main stabilizer to the knee in resisting posterior translation of the tibia on the femur. It provides 95% of total restraining force to straight posterior translation of the tibia relative to femur. Secondary restraints to posterior displacement of the tibia include posterolateral capsule, popliteus, MCL, and POL (posterior oblique ligament). It has secondary functions of resisting varus and Vagus forces, as well as resisting external rotation.
The PCL originates on the medial aspect of the femoral condyle and inserts onto the posterior aspect of the tibia. There are two bundles of the PCL: the anterolateral and the posteromedial (in contrast to the anteromedial and posterolateral bundles of the ACL). The anterolateral bundle is the main resister to posterior translation when the knee is flexed whereas the posteromedial bundle is tight in extension.
In contrast to the ACL which is extrasynovial, the PCL is intrasynovial which makes its healing potential better then that of the ACL.
The PCL is usually torn with an anterior directed blow to the knee with the knee bent. This can occur with a MVC when the knee hits the dashboard, or it can commonly occur in football. In fact, many professional lineman have partial PCL injuries that have largely gone unnoticed. The PCL is often injured in conjunction with the posterolateral corner (multiple ligamentous and tendinous structures of the posterolateral knee) which must be carefully evaluated as well.
PCL tears are evaluated by clinical exam by doing a posterior drawer test: posterior force applied to the tibia with the knee in 90 degrees of flexion. MRI imaging can give better characterization of the injury.
PCL tears are treated with reconstruction when necessary. If patients are symptomatic, or in other words, have feelings of instability secondary to PCL injury, the PCL can be reconstructed with an all arthroscopic technique, or with a combination of open tibial inlay technique in conjunction with arthroscopic assistance.
References
http://www.wheelessonline.com/ortho/posterior_cruciate_ligament