Arthritis and Other Joint Problems - Posterior Cruciate Ligament Tears
Introduction
It takes a sharp blow to tear the posterior cruciate ligament (PCL), so this type of injury is rare. It is usually seen only after a serious car accident or bad fall. Damage to the PCL is often accompanied by a torn meniscus.
Anatomy
As discussed in the Anatomy section in The Knee Joint, ligaments hold the bones of the knee in place. The PCL keeps the lower leg bone (tibia) from moving too far back in relation to the upper leg bone (femur). If the tibia does move too far back, the PCL can tear.
CausesA direct blow to the front of the leg while the knee is bent is the most common cause of a PCL injury. In a car accident, for example, the driver or front passenger may hit a bent leg against the dashboard just below the kneecap. The impact forces the tibia backward from alignment with the femur, ripping the PCL. Another common cause of a PCL tear: falling directly on a bent knee. |
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Symptoms
Although symptoms are not the same in every person with a PCL tear, you'll probably experience pain and swelling for 2 to 4 weeks after your injury. Your knee may also be unstable, sometimes collapsing or "giving way" when you walk. This instability rarely gets better on its own, and usually needs additional treatment.
Diagnosis
As discussed in Arthritis and other Joint Problems, your doctor will take a history and perform a physical exam to make the diagnosis. He'll examine your knee to see if it is unstable, which might indicate a PCL tear.
An x-ray will rule out a broken bone, but won't show a torn PCL. An MRI, which shows ligaments and other soft tissues in the body, is needed for a picture of the injury.
Treatment
Resting the knee gives the ligament time to heal. Ice applied 2 or 3 times a day for 15 to 20 minutes may decrease pain and swelling. Compressing the knee with a bandage or brace can limit swelling.
You may also need crutches to keep weight off your knee. When using crutches, put your weight on your arms and hands rather than your armpits and bend your elbows. Keep your injured leg off the floor by bending your knee. Move both crutches forward. Then swing your uninjured foot between the crutches, landing heel first.
For a small, isolated PCL tear, an exercise program to regain motion and strengthen the thigh (quadriceps) muscle is usually successful. Your doctor will probably recommend some exercises. You may also have to wear a knee brace if your lifestyle includes playing pivoting sports (such as basketball).
If your knee remains unstable despite nonsurgical treatment, you may need surgery. Repairing a PCL is most often done using arthroscopy. For more on this procedure, see the section on Arthroscopy. Patients often go home after the operation. Occasionally, they need to stay in the hospital overnight. In most cases, the doctor will replace the torn PCL with a piece of tendon or ligament from elsewhere in your knee, or with a piece of tissue donated by someone else to a tissue bank.
To restore motion and strengthen the knee muscles after surgery, your doctor will recommend exercises.
