KNEE CAP PAIN

Report #6538

The most common long-term running injury is called runner's knee and is caused by the back of the knee cap rubbing against the femur, the long bone behind it.

When you suffer from runner's knee, the back of the kneecap hurts when you walk or run, particularly when you walk down stairs. It usually does not hurt to pedal a bicycle. If it hurts to push the kneecap against the bone behind it, you have runner's knee.

The back of the kneecap is shaped like a triangle with the point fitting in a grove in the lower part of the bone behind it. During running, the knee cap is supposed to move up and down and not side to side/ and touch the front of the bone behind it. If it does, the back of the kneecap will rub against the front of the bone behind it and hurt. Treatment is to stop the kneecap from touching the bone behind it which is usually caused by the knee cap being pulled toward the outside laterally/ while the lower leg twists the bone behind it inward medially. When you run, you land on the lateral bottom of your foot and roll inward, causing the lower leg to twist inward. At the same time, three of the four quad muscles attached to the kneecap pull the kneecap outward and cause the knee cap to rub against the bone behind it. You can keep the knee cap from rubbing by wearing orthotics, special insets in your shoes, doing exercises to strengthen the muscle that pulls your knee cap inward and by running backwards rather than forward.

By Gabe Mirkin, M.D., for CBS Radio News