By Robert Dow Hoffman, M.D.
Every year doctors treat roughly 100,000 Americans who suffer injuries to the anterior cruciate ligament (ACL) of the knee. This ligament is located inside the knee joint and forms an important part of the connection between the thigh bone (femur) and shin bone (tibia). It helps prevent the tibia from sliding forward on the femur during many physical activities and sports. For a variety of reasons, this ligament does not heal on its own after injury, and about half of the people who suffer an injury to this ligament eventually undergo surgery to reconstruct it.
A large number of knee ligament injuries occur during contact sports such as football. This is obvious to anyone who watches college and professional football on the weekends during the fall. However, about 70 percent of ACL injuries occur in the absence of contact with another player or object, so called non-contact injuries. The ACL is a particularly important stabilizing structure for the knee during sports and activities, such as soccer and basketball, that require quick changes in speed and direction as well as jumping. Consequently, many of these non-contact injuries occur when a person lands from a jump, attempts to change direction quickly, or tries to stop or slow down while running.
Most muscle, bone, and joint injuries appear to affect men and women participating in a given sport at roughly the same rate. However, recent research has demonstrated that this is not the case in non-contact injuries to the anterior cruciate ligament. Data collected over the past ten years indicates that the rate of injury to the ACL for men and women is significantly different in many of the popular sports in this country. For instance, the rate of non-contact ACL injury in basketball for women is roughly twice that of men. In soccer, the rate of ACL injury for women is about four times that of their male counterparts.
How do we explain this? In short, no one knows for sure. A number of theories have been put forth in recent years but none can entirely account for the significant difference in injury rates between the sexes. Some researchers have suggested that anatomic differences between men and women predispose women to these injuries. On average, female knees and ACLs are smaller than those of men and therefore may be more prone to injury.
Although this sounds logical, the current data available have yet to confirm this. Other researchers have suggested the possibility of hormonal influence on these injuries, but again, this has not been conclusively demonstrated. Thigh muscle strength and activity have also been implicated as possible contributing factors. One recently published article in the American Journal of Sports Medicine notes that women who are loose jointed and heavy for their given height may be particularly at risk.
What can a person do to prevent an injury to the ACL? Over the past 15 years or so, literally thousands of research studies have been published relating to the ACL, but very few deal with injury prevention. Most experts agree that wearing a brace does not prevent injury to the ACL. Improving strength and coordination of the hamstrings, the large muscles on the back of the thigh, may decrease the risk of injury. Current research continues to look for an explanation of the difference between the sexes and ways to prevent these injuries.
After an injury to the ACL, both surgical and non-surgical treatment options are available. Non-surgical treatment is usually considered for patients who do not place great demand on their knees. In these cases, a physical therapy program emphasizing muscle strengthening and coordination will allow the patient to return to their previous level of activity. For those people who desire a return to sports requiring jumping and quick changes in speed and direction, surgical reconstruction of the ACL is recommended. Portions of tendons located around the knee can be used to create a new ACL which can then be placed in the knee with the help special instruments and a small camera called an arthroscope (shown above). This procedure is successful in about 90 percent of patients, restoring stability to the knee and allowing patients to return to their previous level of physical activity. Although the incidence of injury to the ACL between men and women is different, the outcome is essentially the same for both sexes.
For more information on ACL injuries or any other orthopedic concerns – either male or female – contact Dr. Hoffman at Chatham Orthopedics, 4425 Paulsen Street, Savannah, GA 31405; 912-355-6615.