Ligaments are tough, nonstretchable fibers that hold your bones together. A tear to the anterior cruciate ligament (ACL) of your knee joint is among the most common sport-related injuries. The ACL connects the thighbone (the femur) to the shinbone (the tibia) and acts to prevent your thighbone from moving too far forward over the knee joint. This ligament also helps stabilize the shinbone from rotating out of the knee joint.
The ACL can tear when it’s stretched beyond its normal range. This typically happens by sudden twisting movements, slowing down from running, or landing from a jump. You may hear a popping sound at the time of injury. Your knee may give way and begin to swell and hurt.
Because the ACL is not capable of healing itself (ligaments, unlike muscles, do not have their own blood supply), it can only be reconstructed (that is, replaced) surgically — it cannot simply be repaired. Less active people may choose to treat a torn ligament nonsurgically with a rehabilitation program focusing on muscle strengthening and lifestyle changes. Surgical reconstruction, however, may help many people recover full function after an ACL tear. Your doctor can discuss these different options with you and help choose what is right for you.
After ACL reconstruction, performing rehabilitative exercises may gradually return full flexibility and stability to your knee. Building strength in your thigh and calf muscles to support the reconstructed knee is a primary goal of rehabilitation. You may also need to use a knee brace for a short time, and it is important not to return to full activity too soon to prevent reinjury.