Surgical Procedures - Anterior Cruciate Ligament (ACL) Reconstruction

ANATOMY OF THE KNEE JOINT The knee joint is one of the body’s largest moveable joints. This joint is essentially made up of three bones: the femur (thigh bone), the tibia (shin bone), the patella (knee cap). The weight-bearing surfaces of the knee joint are covered with a smooth, slippery articular cartilage that allows the bones to slide freely on each other. Another type of cartilage called the meniscus, lies between the femur and tibia, and cushions the joint. The joint cavity is lubricated by a substance called synovial fluid, which further reduces friction. The knee joint is held together by the muscles and tendons and strong, fibrous structures called ligaments. Internally, the anterior cruciate and posterior cruciate ligaments hold the joint together in its normal anatomical position and prevent dislocation. These ligaments cross the joint, and stabilize the knee as it is flexed (or bent) and extended (or straightened). When the leg flexes at the knee, it does not only bend and straighten in one plane, but there is also a slight rotational component to this action as well.

THE ANTERIOR CRUCIATE LIGAMENT INJURY When a severe twisting of the knee occurs, one or both of these ligaments (ACL and PCL) may become stretched, or even torn. This twisting of the knee may be related to a contact injury (such as might occur in football), or even a non-contact injury. Some patients report of hearing a “pop” or “snap” when the injury occurred. Following the injury, the injured knee joint may swell and feel like it may “give way” when weight is applied.

A tear in the anterior cruciate ligament (ACL) is one of the most common knee injuries that may occur to a recreational, amateur, or professional athlete. This injury may result from twisting the knee too far in one direction, or by a sudden and forceful change in direction as may occur during football, soccer, skiing, basketball, racquetball, or tennis. Frequently, the injury occurs in those sports that require the foot to be planted in one spot, and the body to suddenly change direction or make a lateral movement. This anterior cruciate ligament is a thick fibrous band that connects the femur (the thigh bone) with the tibia (shin bone). If the ACL is completely torn, the knee becomes unstable. Because long-term instability may lead to early arthritis of the knee, a proper diagnosis is necessary to obtain the best possible outcome. By recognizing the instability and reconstructing the ACL, the chance of degenerative changes in the joint are reduced. A small percentage of people may be able to function with a torn ACL; however, this usually requires modification of activity.

WHEN SURGERY IS INDICATED Reconstruction of the knee joint following complete ACL rupturing, may require surgery to replace the stabilizing effect of the original ACL. During surgery, a bone and soft tissue graft is taken (or harvested) from the anterior knee. A small portion of bone is taken from both the patella (knee cap) and tibia (shin bone). The drawing on the left depicts the location of this graft site. The bone grafts are connected to each other by a piece of strong patellar tendon. This graft with its three components will now serve as the new ACL ligament. CLICK HERE to continue with our section describing ACL reconstruction.