What Is a 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 posterior, or 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 (Orthogate, 2006).

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

    What Causes a PCL Injury?

    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, such as jumping.

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

    Symptoms of a PCL Injury

    Symptoms of a PCL injury can be mild or severe, depending on the severity of the injury. If the ligament is mildly sprained, symptoms might be nonexistent. 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

    Diagnosing a PCL Injury

    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

    Preventing a PCL Injury

    It is difficult to prevent ligament injuries because they are often the result of an accident or unforeseen circumstance. However, several preventive measures can help minimize the risk of a knee ligament injury:

    • using proper technique/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, such as football, skiing, and tennis

    Treating PCL Injuries

    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 and/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—this surgery is usually done on an outpatient basis using an arthroscope, a small fiber-optic camera that can be inserted into the joint. The surgeon uses a piece of tendon from another part of the knee or sometimes from a donor to replace the damaged portion of the PCL.

    In PCL injuries, the major symptom 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.

    Outlook for a PCL Injury

    For minor injuries, the ligament may heal without complications. However, it is important to note that if the ligament was stretched, it may never regain its prior stability. This means it is more likely that the knee will 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 do not 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 severity of the surgery and of the original injury. 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 are more severe.