An ACL injury is the over-stretching or tearing of the anterior cruciate ligament in the knee.
The ACL typically sprains during one of the following knee movements: a sudden stop; a twist, pivot or change in direction at the joint; hyperextension; or a direct impact to the outside of the knee or lower leg. Sometimes the injury is so severe, the ligament can split or tear.
Pain, swelling, and a loud pop or snap are symptoms of an ACL tear. Usually these are accompanied with a feeling of looseness in the joint and the inability to put weight on the injured knee.
Initial treatment of a torn or sprained ACL may include resting the knee, applying ice, using gentle compression, elevating the leg, and taking anti-inflammatory pain medicines.
Crutches or splints may be used for the first few weeks, but if used for too long, crutches and splints can weaken the muscles from too little activity and the knee will become stiff and restricted. Surgery to reconstruct the ACL and repair other injuries, such as a meniscus tear may also be recommended.