This type of injury results from the tearing of the posterior cruciate ligament (PCL) in its fibers or at its attachment to the femur or tibia.

The PCL is one of the 4 major ligaments of the knee that provide stability for the joint. The PCL restrains the tibia (the larger bone of the lower leg) from slipping backward on the femur (thighbone). The PCL is strong and not commonly injured. Although it can be torn alone, more often the PCL is torn in association with one of the other major ligaments.

What are the causes and risks of the injury?

The injury usually occurs after a fall on the knee or a strong blow to the front of the lower leg, just below the knee. This injury often occurs during sports or running.

If untreated, the knee may repeatedly give way. This can lead to additional injury and possible arthritis.