Doctors have long wondered why women are eight times more likely than men to injure their anterior cruciate ligament (ACL) when playing sports. Mounting evidence suggests that biology could be partly to blame.
Results from a study on women and ACL tears were presented at the recent annual meeting of the American Orthopaedic Society for Sports Medicine in Colorado. Dr. Edward Wojtys of the University of Michigan headed up the study, which revealed that women are three times more likely to tear the ACL during ovulation than at other times of the month.
“Women are up to eight times more likely to sustain this knee injury than men—and now there is mounting evidence that hormonal activity, particularly the increase in estrogen seen mid-cycle, may play a role in increasing the risk of this injury,” Wojtys told HealthScout.
The study involved 65 women between the ages of 18 and 38 with acute ACL injuries. Researchers tracked their hormone levels through urine samples taken within 24 hours of injury. Through measurement of estrogen, progesterone, and lutenizing hormone metabolites, researchers concluded that women were at a greater risk of ACL injury during days 10 through 14 of the menstrual cycle (ovulation) and at a lesser risk during days 15 through the end of the cycle.
Experts involved with the study do not believe that ACL injuries in women can be blamed entirely on hormones. Because women sustain ACL injuries throughout the menstrual cycle, hormones are most likely only part of the answer.
“There are a variety of intrinsic factors involved here—hormonal, anatomic, muscle factors—plus we can’t forget training differences in men and women, with women generally taking up sports at a later age than men,” Dr. Elliott Hershman of Lenox Hill Hospital in New York told HealthScout.
The study also showed that birth control pills might have a positive, protective effect on the knees. Fourteen of the women involved in the study were taking oral contraceptives at the time of injury. Their rate of mid-cycle ACL injury was significantly lower than that of women who were not taking birth control pills.
Dr. Wojtys cautions against misreading the results of the study: “We don’t want this material to press the panic button. This research does not justify pulling young ladies out of sports or putting young women on oral contraceptives to prevent ligament injuries.”
ACL injury is damage to the ligament that provides stability to the knee. It usually results from a twisting or impact injury. It can be an incomplete injury (sprain), partial tear (avulsion), or a complete tear. If an athlete’s muscles are not properly conditioned, jumping or cutting motions may cause a serious ACL injury.