Posterior Cruciate Ligament Injury

The posterior cruciate ligament (PCL) is the strongest ligament in the knee joint. Ligaments are thick, strong bands of tissue that connect bone to bone. The PCL runs along the back of the knee joint from the bottom of the thighbone (femur) to the top of the lower leg bone (tibia).

The PCL helps keep the knee joint stable, especially the back of the joint. An injury to the PCL could involve straining, spraining, or tearing any part of that ligament. The PCL is the least commonly injured ligament in the knee.

A PCL injury is sometimes referred to as an "overextended knee."

The main cause of PCL injury is severe trauma to the knee joint. Often, other ligaments in the knee are affected as well. One cause specific to PCL injury is hyperextension of the knee. This can occur during athletic movements like jumping.

PCL injuries can also result from a blow to the knee while it is flexed, or bent. This includes landing hard during sports or a fall, or from a car accident. Any trauma to the knee, whether minor or severe, can cause a knee ligament injury.

Symptoms of a PCL injury can be mild or severe, depending on the extent of the injury. Symptoms might be nonexistent if the ligament is mildly sprained. For a partial tear or complete tear of the ligament, common symptoms include:

• tenderness in the knee (specifically the back of the knee)
• instability in the knee joint
• pain in the knee joint
• swelling in the knee
• stiffness in the joint
• difficulty walking

To diagnose a PCL injury, your doctor will perform a variety of tests, including:

• moving the knee in various directions
• physical examination of the knee
• checking for fluid in the knee joint
• an MRI of the knee
• an X-ray of the knee joint to check for fractures

It’s difficult to prevent ligament injuries because they are often the result of an accident or unforeseen circumstance. However, preventive measures that can be taken to help minimize the risk of a knee ligament injury include:

• using proper technique and alignment when doing physical activities, including walking
• stretching regularly to maintain good range of motion in the joints
• strengthening the muscles of the upper and lower legs to help stabilize the joint
• using caution when playing sports in which knee injuries are common like football, skiing, and tennis

The treatment for PCL injuries will depend on the severity of the injury and your lifestyle.

For minor injuries, treatment may include:

• splinting
• applying ice
• elevating the knee above the heart
• taking a pain reliever
• limiting physical activity until pain and swelling are gone
• using a brace or crutches to protect the knee
• physical therapy or rehabilitation to strengthen and regain range of motion

In more severe cases, treatment may also include:

• physical therapy or rehabilitation to strengthen and regain range of motion
• surgery to repair a torn ligament
• an arthroscope, a small fiber-optic camera that can be inserted into the joint

The major symptom of PCL injuries is joint instability. Many of the other symptoms, including pain and swelling, will go away with time, but instability may remain. In PCL injuries, this instability is often what leads people to elect surgery. Untreated instability in the joint may lead to arthritis.

For minor injuries, the ligament may heal without complications. It’s important to note that if the ligament was stretched, it may never regain its prior stability. This means it’s more likely that the knee may be somewhat unstable and could be easily injured again. The joint could become swollen and sore simply from physical activity or minor injury.

For those with major injuries who don’t have surgery, the joint will most likely remain unstable and be easily reinjured. You will be less able to do physical activities and pain could result from even minor activities. You may have to wear a brace to protect the joint during physical activity.

For those who have surgery, the prognosis depends on the success of the surgery and of the associated injuries to the knee. Generally, you will have improved mobility and stability after the joint is repaired. You may need to wear a brace or limit physical activities in the future to help prevent reinjuring the knee.

For knee injuries involving more than just the PCL, treatment and prognosis may be different because those injuries maybe more severe.