Female athletes have been found to be 1.5 to 2 times likelier to develop an anterior cruciate ligament (ACL) injury than their male counterparts, and researchers say this is because the hormone estrogen weakens the ligament.
In a study published in the American College of Sport Medicine's official journal, Medicine & Science in Sports & Exercise, the researchers found women, not just athletes, who use birth control pills were less likely to suffer serious knee injuries because the medication lessens and stabilizes levels of estrogen in the body.
The ACL connects the top and bottom parts of the knee. Damaging it is a serious setback to athletes, with return-to-play rates as low as 49 percent after an ACL injury for soccer players. Aside from career-altering effects, ACL injury may also lead to long-term issues like early onset arthritis, altered walking gait and knee instability.
For the study, the researchers examined data from a national insurance claim and prescription database involving 23,428 women 15 to 19 years of age.
They found that those taking birth control pills were less likely to require corrective surgery for ACL injuries compared to women of the same age with the same injury but not taking birth control pills. And where corrective surgery is needed, women were 22 percent less likely to be on birth control than those also in the 15 to 19 age group.
According to lead author Aaron Gray, puberty helps explain the high incidence of ACL injuries in the age group because it is characterized by not only a sharp increase in levels of estrogen but growth spurts in the legs as well. As such, teens take time learning how to properly use their newly elongated limbs and develop good coordination.
The researchers' proposal that estrogen weakens the ACL was also supported by an earlier study that reported ACL injuries in women spike at times when levels of estrogen are high in their menstrual cycle.
"Young athletes currently use birth control pills for various reasons ... Injury risk reduction could potentially be added to that list with further, prospective investigations," said Gray.
Other authors for the study include Jacques Baillargeon and Zbgniew Gugala.
Photo: Stuart Grout | Flickr
