The posterior cruciate ligament (PCL) is about two inches long and connects the femur to the tibia at the back of the knee. It limits the backward or posterior motion of the tibia (shinbone). Twisting or overextending the knee can cause the PCL to tear, leaving the knee unstable and potentially unable to support a person's full body weight. The PCL is the strongest ligament in the knee, and tears often are associated with traumatic injuries rather than sports injuries. PCL tears can happen when the knee is violently forced backward or when the front of the shin is hit hard, for example when the knee strikes the dashboard during a car accident.
Since PCL tears usually result from a violent blow to the knee, they are often accompanied by injuries to other knee ligaments. Although rare, PCL tears can occur when playing rugby, football or other contact sports.
Symptoms of a PCL tear can vary; the most obvious include pain, swelling and a feeling of unsteadiness in the knee.
Because the PCL is located inside the knee joint, which may be very swollen and painful, it can be difficult to diagnose a PCL tear solely by physical examination. That said, your doctor will do a posterior drawer test, where he or she pushes the shinbone or tibia back while the knee is bent 90 degrees. If the tibia moves more than five millimeters backward, it is likely that the PCL has been torn. Your doctor may perform other maneuvers to test for PCL insufficiency as well.
Isolated PCL tears are usually treated with rehabilitation rather than surgery. However, your doctor may recommend surgery if you have other ligament injuries along with the tear. The surgical procedure usually will reconstruct your PCL using a graft from another part of your body (called an autograft) or a cadaver (called an allograft). The graft serves as a scaffold for the PCL reconstruction, and the type of graft used is based on patient and surgeon preference.
Although the decision to have surgery is often a personal choice, factors such as age, physical condition and athletic goals will help you and your doctor determine the best treatment for your situation. People who are not very active may choose an exercise-strengthening program instead of surgery, since the injury is not likely to interfere with their daily activities. It can take up to six months to complete this type of program.
Reviewed by health care specialists at UCSF Medical Center.