Last month, I had surgery to repair the anterior cruciate ligament in my knee. Now I’m doing a rehabilitation program with a physical therapist. Several exercises are just for my hip and don’t seem to have anything to do with my knee. Are the hip exercises really necessary?

A recent study showed that knee strength is actually affected by the muscles around the hip. For some motions, the hip muscles add only a small amount of strength to the knee. Other knee motions, such as turning the knee in or out (rotation) depend much more on hip muscles.

ACL injury affects the muscles around the knee, especially the thigh muscle (quadriceps). Hip muscle strength may be affected by ACL injury, too. One study showed that hip strength is reduced after knee surgery on the affected side. This is especially true for hip extension, or unbending the hip. This information suggests that hip exercises can help you achieve the fullest recovery from your injury.