Anterior Cruciate Ligament (ACL)

The Anterior Cruciate Ligament (ACL) is a major stabilizing ligament in the knee, connecting the tibia (leg bone) to the femur (thigh bone) and keeping the two appropriately aligned. Located in the center of the knee, the ACL crosses over the Posterior Cruciate Ligament (PCL) – forming an “X” shape. The ACL keeps the tibia and femur in the proper relationship with each other and prevents non-physiologic anterior (forward) movement of the tibia on the femur.

The ACL is much like a tight rope. It can be torn by a sudden contraction of the quadriceps (thigh muscle) at a time when the foot is misplanted on the ground, a sudden change in direction occurs, or an externally applied force is projected directly onto the knee such as in an automobile accident, or when an athlete is struck on the outside of the knee. When the ACL tears, a patient typically reports hearing or feeling a “pop” and explains that the knee “went out,” or dislocated. This is a severe injury, and when it occurs, an athlete typically cannot finish the day’s activities. In the course of these events, injury may also occur to the articular and meniscal cartilages. Left untreated these injuries could eventually lead to posttraumatic arthritis. After this ligament has been ruptured, it is common for the patient to frequently experience recurrent subluxations (a partial or incomplete dislocation) of the knee. This, too, will lead to posttraumatic arthritis.

All ACL injuries require a Reconditioning Program to maintain strength of surrounding muscles and tendons. For athletes and patients not able to drastically change their activities, an ACL Reconstruction followed by Accelerated ACL Rehabilitation is recommended.