14-Mar-07 9:00 AM CST

ACL Tears

Anterior Cruciate Ligament (ACL) Tears
The anterior cruciate ligament (ACL) is the main ligament that controls the rotation of the knee. The ACL is important in providing stability during cutting and pivoting motions of the knee.

What are the other main ligaments of the knee?
   The other main ligaments of the knee are the posterior cruciate ligament (PCL), medial collateral ligament (MCL), and lateral collateral ligament (LCL). These ligaments provide stability to the knee in all directions of motion.

How is the ACL torn?
   ACL tears occur when the knee is twisted inwardly such as in a sports injury or a twisting fall. The knee usually becomes immediately swollen and painful. When the ACL tears, other structures inside the knee such as the meniscus and other ligaments can tear as well. The ACL does not repair itself after it is torn.

What are the symptoms?
   Immediate pain and swelling usually occurs. The knee becomes unstable because the torn ACL no longer controls the rotation of the knee. A feeling of the knee shifting or buckling is common.

How is it diagnosed?
   On physical exam, special tests are performed to determine if the ACL and the other key structures in the knee are intact. The ACL cannot be seen on xray. MRI is used to visualize the ACL as well as the meniscus and other ligaments in the knee.

How is it treated?
   ACL tears in young, active patients are generally treated with surgical reconstruction. In patients with a more sedentary lifestyle, conservative treatment may be recommended initially. If knee instability continues despite nonoperative treatment, then surgery may be necessary.
   ACL reconstruction involves replacing the torn ACL with a tendon graft usually taken from another part of the knee. The tendon graft is passed through bone tunnels in the femur and tibia and secured with a screw on each end. Postoperative recovery is focused on regaining the strength and motion of the knee. Generally, patients are allowed to run after two months, and return to cutting and pivoting activities after four months.