ACL Reconstruction - Basic Information Information

 The anterior cruciate ligament (ACL) of the knee is a critical central stabilizer for twisting and pivoting actions. If torn, patients develop instability with active sports and eventually activities for daily living. Tears of the ACL are often associated with tears of the “shock absorbers” of the knee (the menisci) and/or the collateral ligaments, the inside and outside stabilizers.

A torn ACL has little to no ability to heal itself. The ligament can only be reconstructed or replaced as attempts to stitch it back together have met with unsuccessful results. The diagram below on the left demonstrates a healthy and firmly attached ACL to the femur (upper leg bone) and the tibia (a bone in the lower leg). The ACL on the right is torn and will need to be reconstructed.

Normal ACL

Once a diagnosis is made and surgery recommended, the knee is examined under anesthesia to evaluate the degree of instability and then an arthroscopic surgical procedure is performed. A fiberoptic scope is introduced through a small ¼ inch incision to visually examine the entire inside of the joint. This is to confirm the clinical diagnosis and determine additional damage. Small tunnels are drilled in the tibia and femur. Next, your new ACL is brought through these tunnels and secured. As the healing process takes place, these tunnels fill in to anchor the new ACL.

Drill small tunnels

Insert new ACL

One important step, which differentiates surgeons, is “Where the new ACL comes from.” In choosing a surgeon to perform your ACL surgery, you must be aware of the methods commonly used to create your replacement ACL graft. Graft sources include the patellar tendon, quadriceps tendon, hamstring tendons or a tendon from a source other than your own body (allograft).

In the patellar tendon method, the middle of the tendon attached to the kneecap and upper tibia, called the patellar tendon, is used to replace the damaged ACL. The middle third of the tendon and a small portion of bone on either end is removed and used as the new ACL. This is called a patellar tendon autograft, because is uses your own tissue. It is also referred to as “bone-patellar tendon-bone” method.

 

Patellar Tendon

The quadriceps method involves removing a portion of the quadriceps tendon, which attaches to the top of the kneecap (patella) together with a small portion of the bone from the upper patella to the lower leg. At the present time this is an uncommon graft source.

 

The hamstring method commonly consists of removing both the gracilus and semi-tendinosis hamstring tendons. (The blue area on the diagram.) These small hamstring tendons run from the hip (pelvic) bone down the full length of the inner thigh to attach below the knee on the anterior medial tibia. They assist slightly in hip and knee flexion. These two grafts are doubled to give a quadruple strand of thick graft

These small pes anserine tendons are to be distinguished from the larger and stronger posterior semi-membranosis and biceps femoris hamstring tendon, which still functions normally after ACL reconstruction.
 

Hamstring Tendon

A tendon from another source outside your body. This is referred to as allograft, the tendon does not come from your own body. It comes from a tissue bank or donated tendons.

 

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3/1/2006

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