Girls and women are 2x-6x more likely to have an anterior cruciate ligament (ACL) tear than men in similar sports.
Why?
One cause, say two studies, one from the University of Texas and another from Aarhus University in Denmark may be the level of female hormones. Both studies found that women who took birth control pills reduced their risk of ACL surgery by almost 20%.
The University of Texas study, “Effects of Oral Contraceptive Use on Anterior Cruciate Ligament Injury Epidemiology,” used national claims data from 2002 to 2012 to measure exposure to oral contraceptives and their effect on ACL injury risk. According to their data, published in Medicine & Science in Sports & Exercise, women age 15-19 years old undergoing surgical repair of the anterior cruciate ligament were 18% less likely to use oral contraceptives than matched controls (p < 0.0001).
In the Danish study, “Is the use of oral contraceptives associated with operatively treated anterior cruciate ligament injury? A case-control study from the Danish Knee Ligament Reconstruction Registry,” the researchers also studied women who were operatively treated for ACL injury. This time they measured oral contraceptive exposure at the time of the ACL injury as well as in the 5 years previous. They too found that oral contraceptive users had a reduced risk for ACL injury. The study was published in The American Journal of Sports Medicine.
Need to Establish Protective Effect
Subsequent reviews of these studies, however, pointing to the fact that they were limited by the information in the patients’ records. Another limiting factor was that they only included women who underwent surgery and not those who chose nonsurgical solutions.
The reviewers in one review from Brown University argued that a protective effect was not established. They wrote, “A better understanding of the relationship between oral contraceptive pill use and ACL injury is warranted.”
A recent study in the Physician and Sportsmedicine, “Oral contraceptives provide protection against anterior cruciate ligament tears: a national database study of 165,748 female patients,” however offers more evidence that oral contraceptives do have a protective effect on ACL tear, especially in the 15-19 age group. That study reported that the athletes they studied who used oral contraceptives experienced a 63% reduction in the rate of tear.
The researchers used the PearlDiver Technologies, Inc. database to collect data on all oral contraceptive female users between the ages of 15 and 49. They compared a group of females who were undergoing surgery for an ACL injury who were on oral contraceptives to a group of females having the surgery who were not on birth control.
According to the data collected from 82,874 patients, those who did not take oral contraceptives had 569 (0.69%) ACL reconstructions vs. 465 (0.56%) in the oral contraceptive group (p < 0.001).
Of those patients aged 15 to 19 who took oral contraceptives, 13.33% underwent ACL reconstruction while 29.35% of that group who did not take oral contraceptives underwent ACL reconstruction.
The researchers wrote, “Future prospective studies should be aimed at determining the number needed to treat to truly experience a protective effect. While there are potential risks of oral contraceptives (thromboembolism, weight gain, etc.), those at high risk for ACL tear could potentially benefit from their use.”
They added, “This leads us to conclude that female athletes, specifically in the 15- to 19 year-old age group should be screened for current [oral contraceptive] usage, and that discussion should be had toward potentially beginning [oral contraceptive] usage in female populations at higher risk for injury (soccer players, basketball players, etc.).”
