While researchers have known that female athletes are more likely than male athletes to sustain an injury to their anterior cruciate ligament (ACL), they have not been able to pinpoint why this difference in risk exists, until now.
A new study has found that the primary female sex hormone estrogen might be affecting the strength of this ligament. Although men also have estrogen, their levels are nowhere near as high as the levels that are produced in women. Researchers at The University of Texas Medical Branch at Galveston examined insurance claim data on 23,428 women between the ages of 15 and 19 that were filed from 2002 to 2012.
The research team found that women with ACL injuries who were taking birth control pills had a lower risk of needing corrective surgery when compared to women with the same injuries who did not take oral contraceptives. More specifically, the researchers calculated that women who needed reconstructive ACL surgery were 22 percent less likely to be on birth control pills in comparison to women who were of the same age but were not injured.
"The use of oral contraceptives potentially modifies anterior cruciate ligament injury risk in young women," the study authors wrote. "Despite reports that athletes, who are more prone to anterior cruciate ligament injury, use oral contraceptives at about twice the rate of nonathletes, these data suggest that women ages 15-19 yr undergoing anterior cruciate ligament reconstruction used oral contraceptives at a lower rate than the general population."
Based on these findings, as well as the results from another investigation that found that women had the greatest risk of ACL injuries during menstruation when their estrogen levels were at their highest, the researchers concluded that estrogen can be causing weakness in the ACL.
"Birth control pills help maintain lower and more consistent levels of estrogen, which may prevent periodic ACL weakness," the lead author of the study Aaron Gray said.
"Young athletes currently use birth control pills for various reasons including more predictable cycles and lighter periods. Injury risk reduction could potentially be added to that list with further, prospective investigations," he added.
The researchers stated that since ACL injuries can drastically affect athletes' careers, finding ways to prevent them is crucial in insuring that young athletes can continue to thrive in their respective sports.
The study was published recently in the official journal of the American College of Sports Medicine.
