The anterior cruciate ligament (ACL) is the major stabilizing ligament of the knee.  The ACL is located in the centre of the knee joint and runs from the femur (thigh bone) to the tibia (shin bone), through the centre of the knee.  The ACL prevents the femur from sliding backwards on the tibia (or the tibia sliding forwards on the femur).  Together with the posterior cruciate ligament (PCL), ACL stabilizes the knee in a rotational fashion.  Thus, if one of these ligaments is significantly damaged, the knee will be unstable when planting the foot of the injured extremity and pivoting, causing the knee to buckle and give way. 

An ACL injury is a sports related injury that occur when the knee is forcefully twisted or hyperextended. An ACL tear usually occurs with an abrupt directional change with the foot fixed on the ground or when the deceleration force crosses the knee. Changing direction rapidly, stopping suddenly, slowing down while running, landing from a jump incorrectly, and direct contact or collision, such as a football tackle can also cause injury to the ACL.

When you injure your ACL, you might hear a "popping" sound and you may feel as though the knee has given out. Within the first two hours after injury, your knee will swell and you may have a buckling sensation in the knee during twisting movements.

Diagnosis of an ACL tear is made by knowing your symptoms, medical history, performing a physical examination of the knee, and performing other diagnostic tests such as X-rays, MRI scans, stress tests of the ligament, and arthroscopy.

Treatment options include both non-surgical and surgical methods. If the overall stability of the knee is intact, your doctor may recommend nonsurgical methods. Non-surgical treatment consists of rest, ice, compression, and elevation (RICE protocol); all assist in controlling pain and swelling. Physical therapy may be recommended to improve knee motion and strength. A knee brace may be needed to help immobilize your knee.

The usual surgery for an ACL tear is an ACL reconstruction which tightens your knee and restores its stability. Surgery to reconstruct an ACL is done with an arthroscope using small incisions. An arthroscope is inserted into the knee joint through one of the small incisions to provide clear images of the surgical area (inside the knee) to the surgeon on a television monitor. Guided by these images the surgeon performs the surgery using small surgical instruments inserted through the other small incisions around the knee. Your doctor will replace the torn ligament with a tissue graft that can be obtained from your knee (patellar tendon) or hamstring muscle. Following arthroscopic ACL reconstruction, a rehabilitation program is started to help you to resume a wider range of activities.

As the surgery is performed through small incisions it provides the following benefits:

• Less post-operative pain
• Shorter hospital stay
• Quicker recovery.