“The posterior cruciate ligament (PCL) connects the medial femoral condyle to the posterior intercondylar area of the tibia and is affixed in such a way that the anterolateral section is taut in flexion and the posteromedial section is taut in extension, helping to maintain the correct anatomic relationship between the femur and tibia. The PCL alone provides almost all of the resistance to posterior displacement of the tibia and so is appropriately the strongest of the cruciate ligaments. Tearing or rupture of the PCL can occur with hyperextension, hyperflexion, or rotation applied with a force that is so great that other knee components are also generally injured.
The most common mechanism leading to an isolated injury of the PCL is a direct blow to the anterior tibia with the knee in flexion, like that experienced when the proximal tibia impacts the dashboard in an automobile crash or when an athlete is hit or kicked in the proximal tibia while the knee is in flexion. Athletes with a PCL injury frequently complain of posterior knee pain and pain when kneeling. The presence of painful limitation of flexion and a posterior sag sign (posterior drawer sign) on examination strongly supports a diagnosis of isolated PCL injury.” ABFM
References
Grover M: Evaluating acutely injured patients for internal derangement of the knee. Am Fam Physician 2012;85(3):247-252.