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Related Anatomy of the PCL
To understand how Posterior Cruciate Ligament (PCL) injury can occur, one must consider the anatomical and physiological properties of the PCL. The PCL is located within the knee joint where it stabilizes the articulating bones, particularly the femur and the tibia, during movement. It originates from the lateral edge of the medial femoral condyle and the roof of the intercondyle notch then stretches, at a posterior and lateral angle, toward the posterior of the tibia just below its articular surface.



Related Physiological Features of the PCL
Although each PCLs is a unified unit, they are described as separate anterolateral and posteromedial sections based off where each section's attachment site and function. During knee joint movement, the PCL rotates, such that the anterolateral section stretches in knee flexion but not in knee extension and the posteromedial bundle stretches in extension rather than flexion.

The Types of Mechanisms that Lead to PCL Injury
In this position, the PCL functions to prevent movement of the tibia in the posterior direction and to prevent the tilting or shifting of the patella. However, the respective laxity of the two sections makes the PCL susceptible to injury during hyperflexion, hyperextension, and in a mechanism known as a dashboard injury. Because ligaments are viscoelastic (p. 50 ) they can handle higher amounts of stress only when the load is increased slowly (p. 30 ). When hyperflexion and hyperextension occur suddenly in combination with this viscoelastic behavior, the PCL deforms or tears. In the third and most common mechanism, the dashboard injury mechanism, the knee experiences impact in a posterior direction during knee flexion toward the space above the tibia. These mechanisms occur in excessive external tibial rotation and during falls that induce a combination of extension and adduction of the tibia, which is referred to as varus-extension stress, or that occur while the knee is flexed.