The Anterior Cruciate Ligament (ACL)
Posted on Wed, Oct 27, 2010 @ 03:35 PM
WHAT IS THE ACL?
ACL stands for anterior cruciate ligament of the knee. The knee is the largest and most complex joint in your body. It depends on four primary ligaments as well as multiple muscles, tendons and secondary ligaments to function properly. There are two ligaments on the sides of the knee: the medial collateral ligament (MCL) and the lateral collateral ligament (LCL), and two crossed ligaments in the center of the knee: the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). The ACL connects the front top part of the shin bone to the back bottom part of the thigh bone and keeps the shin bone from sliding forward.
ACL INJURY RATES
The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the knee. Approximately 150,000 ACL injuries occur in the United States each year. Female athletes participating in basketball and soccer are two to eight times more likely to suffer an ACL injury compared to their male counterparts. Recent data from the Women’s National Basketball Association (WNBA) indicates white European-American players may be at increased risk for ACL injury compared with African- American, Hispanic or Asian players. Athletes who have suffered an ACL injury are at increased risk of developing arthritis later on in life, even if they have surgery for the injury.
HOW DO ACL INJURIES OCCUR?
One of the common ways for the ACL to be injured is by a direct blow to the knee, which can frequently occur in football. In this case, the knee is forced into an abnormal position that results in the tearing of one or more knee ligaments. However, most ACL tears actually happen without contact between the knee and another object. Such noncontact injuries happen when the running athlete changes direction or hyperextends their knee when landing from a jump. These movements are common to all agility sports.
HOW IS AN ACL TEAR DIAGNOSED?
Discomfort after an ACL tear is usually severe enough that the injured person will seek medical attention. The physician will examine the knee, and, in most cases, be able to identify which ligaments are injured. However, there may also be injuries to the joint surface that are more difficult to diagnose. At times, swelling may make it difficult to diagnose a tear. This will necessitate the use of an MRI scan or arthroscope to ensure that an accurate diagnosis is made.
WILL I NEED SURGERY?
The most frequent question after an ACL injury is “Will I need surgery?” The answer varies from person to person. Many factors must be considered by the patient and the physician when determining the appropriate treatment. These factors include the activity level and expectations of the patient, the presence of associated injuries (cartilage tears, etc.) and the amount of abnormal knee laxity. A young patient with an ACL tear and knee laxity who wants to return to competitive sports is more likely to require surgery for a satisfactory outcome. The older patient who can return to limited activity is less likely to require surgical stabilization. In either scenario, rehabilitation of the knee begins with exercises to help restore full range of motion. This is followed by strengthening exercises for the muscles around the knee. Return to sports with or without a brace is allowed only after leg strength, balance, and coordination have returned to near normal.
-Keith Monchik, MD