Anterior cruciate injury: A knee injury involving the anterior cruciate ligament (ACL). The ACL runs diagonally deep inside the knee from the center of rotation of the end of the femur (the thigh bone) to the top of the tibia (the larger bone in the lower leg).
Females are seven times more likely to suffer an ACL injury than their males. The reasons are complex. Women have looser knee joints. In females the Q angle (for quadriceps) is greater and tends to pull the kneecap (patella) out to the side. Their hamstring muscles are generally weaker than their quadriceps, which adds stress to the joint. When men jump they land on both legs with their knees bent, while women land with their knees in a straighter position, putting more stress on the knee joint.
Initial treatment includes ice and anti-inflammatory drugs. The next phase is usually stretching, exercise and physical therapy to rebuild strength and regain motion. The ACL does not heal on its own, but the surrounding knee muscles can be built up through exercise and physical therapy, a process that can take up to a year. Severe ACL injuries, that are complete tears, especially in younger patients, may be surgically repaired. The surgery, usually done by arthroscopy, replaces the ACL with cadaver parts or the patient's hamstring or patella tendons. Rehabilitation takes at least 6 months.