Overview, Causes, & Risk Factors

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.

Symptoms & Signs

What are the signs and symptoms of the injury?

Immediately after injury, the knee swells rapidly over the next 3 to 6 hours. Swelling makes the knee stiff and painful, with difficulty walking. A later result is pain and weakness. The knee sometimes dislocates at the time of the tear.

Diagnosis & Tests

How is the injury recognized?

Diagnosis is based initially on history and physical exam. A bruise on the front of the leg just below the knee may be noticed as well as a swollen knee joint. Joint x-rays may be normal. Sometimes swelling or a chip of bone broken off the tibia at the back of the knee joint may be shown. An MRI scan confirms the diagnosis.

Prevention & Expectations

What can be done to prevent the injury?

Pre-season conditioning before participating in a sport is the best prevention. Sports safety guidelines for adults, adolescents, and children should be followed.

Treatment & Monitoring

What are the treatments for the injury?

Treatment depends on the degree of instability, the person's age, and anticipated future activities. Initial treatment is a brief period of RICE (rest, ice, compression, and elevation). Non-steroidal anti-inflammatory medications (NSAIDs) can help relieve pain. An exercise program may help to regain motion and strength of the knee, especially the upper thigh. For the young athlete, surgical reconstruction of the ligament may be appropriate. In an older, non-athletic person, a non-surgical approach may be chosen, such as a brace. Physical therapy is generally ordered after surgery.

What are the side effects of the treatments?

NSAIDs may have adverse effects on the stomach, liver, or kidneys.

What happens after treatment for the injury?

PCL injury can result in serious damage to the nerves or the artery behind the knee. Treatment may not be successful in restoring stability to the knee. Stiffness and weakness of the knee may remain. Infection is possible after any operation.

The person will be asked to observe for symptoms of instability, with repeated episodes of pain, swelling, giving way, or locking of the knee.