Randy Booth, Dvir Chen, Axel Schaefer, Adam Schultz
Functional Anatomy and Biomechanics
The PCL is a complex ligament comprised of bands of dense connective tissue that originates on the medial femoral condyle and courses posteriorly, laterally, and distally across the joint to insert on the posterior tibia and posterior horn of the lateral meniscus. The PLS consists of passive and dynamic stabilizers that complement the PCL by providing essential posterolateral stability to the knee. The passive structures include the lateral collateral ligament (LCL), the arcuate ligament complex, the fabellofibular ligament, the oblique popliteal ligament, the posterior horn of the lateral meniscus and the posterolateral joint capsule. The dynamic stabilizers include the popliteus complex, the biceps tendon and illiotibial tract (Margheritini, Rihn, & Musahl, 2002).
The PCL serves as a primary restraint to posterior tibial translation and a secondary restraint to tibial external rotation, varus rotation, and hyperextension (Grood, Stowers, & Noyes, 1988). The PCL functions with the PLS to provide an adequate restraint to these forces. The majority of the literature describes the PCL as comprised of two bundles, a larger anterolateral band and a smaller posteromedial band. In the flexed knee the tension of the anterolateral bundle is increaed while with the knee extended the posteromedial bundle is taut (Girgis et al, 1975; Convey & Sapega, 1994). The fiber orientation of these bundles and resultant tensioning patterns forms the clinical hypothesis to support the greater prevalence of partial PCL ruptures (Ritchie, Bergfeld, Kambic and Manning, 1998). In a PCL deficient knee, primary restraint responsibility is shifted entirely to the PLS (Margheritini, Rihn, & Musahl, 2002).
