It is a well-known fact that women athletes are at greater risk for knee injuries compared with men. In particular, anterior cruciate ligament (ACL) injuries seem to plague female athletes much more often than men. In this article, orthopedic surgeons from the Department of Orthopaedics and Rehabilitation at Yale University review the risk factors and biomechanical differences between men and women. They also provide a treatment protocol for successful prevention of this problem.

There are two types of risk factors that contribute to the sex differences in rates of ACL injuries between men and women. The first is intrinsic, meaning things inside the body that affect the ACL. Intrinsic risk factors include anatomic and biomechanic variables. For ACL injuries, research has shown that the number of degrees of the Q-angle, the geometry of the intercondylar notch, the size of the ACL, and the slope of the tibia are contributing factors.

Hormone differences between men and women and genetic predisposition may be two additional risk factors. But data collected from studies so far has been insufficient to prove or disprove the role of either one in ACL injuries.

Extrinsic risk factors remain under investigation, too. One thing we know that does NOT seem to bear any influence on ACL injuries is the lack of playing experience among women. The rate of ACL injuries among women hasn't changed in the last 15 years. The number of females participating in sports HAS increased and along with that increase has come more injuries (not less as you might expect with increased experience).

Other extrinsic factors under consideration include shoe-to-playing surface interaction (increased friction) and shoe construction. Shoes with larger cleats and more cleats seem to increase torsional force on the knee (transferred up to the knee from the foot-to-surface effect). There is even evidence that turf surface and climate (dryer climate) can increase the shoe-playing torsional factor.

What can be done to help prevent ACL injuries among female athletes? Physiotherapists have identified landing position as a key area to focus on. When female athletes jump and land with both feet in control, both hips and knees deeply bent and facing straight ahead, and equal weight on both feet, there are fewer injuries.

But if even one leg is out of balance or the landing is compromised in any way, then the risk of ACL injury increases dramatically. The two different positions are referred to as the position of safety and the position of no return. Teaching women how to stay in the safety position (and having them practice this position daily) has proven to be successful in preventing ACL injuries.

This type of neuromuscular and proprioceptive training under the guidance of a physiotherapist significantly decreases the incidence of ACL injuries in soccer and basketball players. Studies show up to an 88 per cent reduction of ACL injuries in the first year the prevention program was started.

Additionally, it has been determined that for the best results, the prevention program must be done three times a week for 10 minutes over a period of at least two months. The neuromuscular and proprioceptive program of exercises should be accompanied by other exercises as well (e.g., agility drills, core training, plyometrics). And a maintenance program is advised to avoid the effects of deconditioning.

The authors do mention the role of surgery (type of surgery, potential complications of surgery, and expected outcomes with surgery). But the main focus of their review was on identifying and preventing intrinsic and extrinsic risk factors with conservative (nonoperative) care.

Reference: Karen M. Sutton, MD, and James Montgomery Bullock, MD. Anterior Cruciate Ligament Rupture: Differences Between Males and Females. In Journal of the American Academy of Orthopaedic Surgeons. January 2013. Vol. 21. No. 1. Pp. 41-50.

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