Can ACL Tears Be Prevented?

Question: Can ACL Tears Be Prevented?

The anterior cruciate ligament, also called the ACL, is one of four major ligaments of the knee. Injuries to the ACL can be devastating, and may require surgery and a prolonged rehabilitation. Rates of ACL tears are especially high in women; about 8 times as frequent when compared to men. Why do women injure their ACL more frequently? Can these ACL tears be prevented?

Answer: ACL prevention has been the focus of many researchers in the past decade. Understanding how to prevent ACL tears requires an understanding of why some groups of people are more prone to sustaining ACL tears than others. Women have been shown to have a much higher risk of developing an ACL tear, and research has focused on answering the question as to why they have a high risk.

Why do women have a higher risk of ACL injury?

• Anatomic Differences
  There are many anatomic differences between men and women, including pelvis width, Q-angle, size of the ACL, and size of the intercondylar notch (where the ACL crosses the knee joint). Limited studies have shown a difference in these factors, but not an ability to predict individuals who will sustain an ACL tear.

• Hormonal Differences
  It is known that the ACL has hormone receptors for estrogen and progesterone, and it has been thought that hormone concentration could play a role in ACL injuries. Studies have shown some differences in rates of ACL injury during different phases of the menstrual cycle. However, there has been some conflicting data, and the effect of hormone concentration on ACL injury risk has yet to be defined.

• Biomechanic Differences
  Stability of the knee is dependent on different factors. The two most important are the static and the dynamic stabilizers of the knee. The static stabilizers are the major ligaments of the knee, including the ACL. The dynamic stabilizers of the knee are the muscles and tendons that surround the joint. Women have been found to have differences in biomechanic movements of the knee seen when pivoting, jumping, and landing -- activities that often lead to an ACL injury.

What can be done to prevent ACL injuries?

The best way found to reduce the risk of ACL injury is with the use of neuromuscular training programs. As stated above, the dynamic stabilizers of the knee are important in helping to control knee stability. Neuromuscular training is the process of teaching your body better biomechanic movements and improved control of these dynamic stabilizers. This is an unconscious process -- not something you can choose to do. However, there are ways to teach your body to have better unconscious neuromuscular control.

Neuromuscular programs have been designed to address deficits in dynamic stabilization of the knee. There are several neuromuscular programs that have been designed, most of which involve stretching, plyometrics, and strengthening. These programs "teach" the athlete how to land from a jumping position, pivot side-to-side, and move the knee without placing as much force on the ACL.

One of the better known neuromuscular training programs, the PEP program, was developed at the Santa Monica Orthopaedics and Sports Medicine Research Foundation. The PEP program stands for Prevent injury, and Enhance Performance.

_Sources:

_{Griffin LY, et al. "Noncontact Anterior Cruciate Ligament Injuries: Risk Factors and Prevention Strategies" J. Am. Acad. Ortho. Surg., May/June 2000; 8: 141 - 150.}

_{Hewett TE, et al. "The effect of neuromuscular training on the incidence of knee injury in female athletes: A prospective study." Am J Sports Med 1999;27:699–706.}