Historically, tears of the anterior cruciate ligament or ACL, have occurred more often in males than in females. In the last twenty years, however, more and more women have participated in sports, and that trend seems to be changing. Woman now sustain ACL tears at rates higher than their male counterparts. Some people have termed the increase number of injuries as an epidemic in women’s ACL tears. The majority of these tears do not occur in a collision-type of injury, but are injuries usually sustained through non-contact trauma, such as a twist or a sudden deceleration and stop.
Currently, there are a number of studies trying to explain why women seem to be more prone to non-contact ACL tears than men. Different theories propose that part of the difference may be explained by the anatomic shape of the knee, which can differ between men and women. Also, the effect of estrogen in a woman’s body may also work against her by softening or weakening ligaments, making them more susceptible to a tear. Some researchers believe that differences in running, jumping, and landing techniques between men and women are responsible for differences in ACL tear rates.
Recently, Dr. Robert Brophy published an article in the Journal of Bone and Joint Surgery studying the differences between sexes in lower extremity alignment and muscle activity during a soccer kick. In this study, video cameras, retro-reflective markers, and electrodes were placed on 13 male and 12 female college soccer players during the action of kicking a soccer ball. What Dr. Brophy found was that male players activate the hip flexors on the inside of the hip in their kicking leg and the hip abductors on the outside of the hip in their supporting leg more than females. Also of interest is that, in the kicking leg, men generated almost four times as much hip flexor activity as females. In the supporting leg, men generated more than twice as much gluteus meatus activation and vastus medialis activation. Dr. Brophy, who himself is a former collegiate and professional soccer player, surmises that the activation of the hip abductors may help protect players against ACl injury. Dr. Brophy is quoted saying “Since females have less activation of the hip abductors, their hips tend to collapse into adduction during the kick, which can increase the load on the knee joint in the supporting leg and potentially put it at greater risk of injury”.
Currently, the American Academy of Orthopaedic Surgeons have supported a program developed in California called the Prevent Injury and Enhanced Performance (PEP) Program that has been effective in reducing ACL injuries in female soccer players. PEP is an alternative warm-up regimen that focuses on stretching, strengthening, and improving balance.
As can be seen, the exact reason why females tend to injury their ACL more than males still has to be determined. Much research is being devoted to this area, and additional studies will certainly be needed before a final answer or reason can be established.
Robert J. Snyder MD, is a Board-Certified Orthopaedic Specialist with Orthopaedic & Spine Center in Newport News, VA. Voted a “Top Doc” in both 2012 and 2013, Dr. Snyder specializes in Partial and Total Joint Replacement, Sports Medicine and conditions pertaining to the Foot and Ankle.