Damage to the anterior cruciate ligament (ACL) is a common yet severe knee injury. Most people who experience a torn ACL recover in 3–12 months, depending on injury severity and goals for rehabilitation.
The knee comprises three bones—the femur or thighbone, the tibia or shinbone, and the patella or kneecap. Tendons join muscles to these bones, while ligaments hold the three bones in place. These ligaments protect the knee joint from excessive rotation. The ACL is one of the ligaments that stabilize the knee joint.
Source: Medical News Today