Is the use of oral contraceptive associated with operatively treated anterior cruciate ligament injury?: A case-control study from the Danish Knee Ligament Reconstruction Registry.
Rahr-Wagner L, Thillemann TM, Mehnert F, Pedersen AB, and Lind M. Am J Sports Med. 2014; 42:2897-2906.
Take Home Message: Women who take oral contraceptives are less likely to sustain an anterior cruciate ligament (ACL) injury than women who do not.
A woman is 2 to 9 times more likely to have an ACL injury than a man, especially in the athletic population. A better understanding of the factors that place women at a higher risk, would allow clinicians to implement more effective preventative measures against ACL injury. Previous literature has shown that collagen synthesis is inhibited when estrogen levels are increased; therefore, Rahr-Wagner and colleagues completed a case-control study to assess the impact of oral contraceptive use on the odds of sustaining an operatively treated ACL injury among women in a national registry. The authors used the Danish Ligament Reconstruction Register and Danish Prescription Registry to identify 4497 women who underwent ACL surgery. Over 8,800 age-matched controls, who had no history of ACL injury, were selected from the Danish Civil Registration System. The authors used the Danish Prescription Registry to determine if the selected individuals used oral contraceptives. Selected individuals were divided into those who ever used oral contraceptives or never used. Among those who ever used oral contraceptives the authors evaluated new users, recent users (took oral contraceptives but stopped), and long-term users. Approximately, 45% percent of the group with an ACL injury used OC compared with ~48% of the control group. After adjusting for important factors (for example, obesity) the authors found that individuals who used oral contraceptives were 11 to 20% less likely to sustain an ACL injury than those who did not take oral contraceptives. These findings were similar for recent users and long-term users. The number of new users were similar between those with and without an ACL injury. Interestingly, using an oral contraceptive for 1 to 4 years may be protective but using an oral contraceptive for more than 4 years did not alter the likelihood of sustaining an ACL injury.
Overall, the authors found that oral contraceptive use has a protective effect against ACL injury. However, one must be cautious before trying to use an oral contraceptive to prevent ACL injuries among women. The two major issues surrounding this data is completeness of information and an inability to assess a patient’s activity level. One major strength of this study was using various Danish registries to develop a large data set; however, patients who did not undergo ACL surgery were omitted in this study. Furthermore, the researchers were unable to determine who was physically active – let alone who was participating in sports. Ultimately, this study indicates that the next step should probably be a randomized clinical trial to test if oral contraceptives can reduce the risk of ACL injuries. In the meantime, clinicians may benefit from using this information more from a diagnostic than preventative perspective. For example, clinicians may ask patients about oral contraceptive use and want to use more ACL diagnostic tests when evaluating knee injuries among athletes who do not use oral contraceptives, as they are at a higher risk. Furthermore, if a patient asks about whether oral contraceptives may help prevent an ACL injury we can use this study to explain that there is some evidence to support this concept but it is unclear if it will hold up in future studies with female athletes.
Questions for Discussion: Do you currently make note of oral contraceptive use during preseason athlete screening? If so, how do you feel this has impacted your ability to prevent, diagnose and treat injuries if at all?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban
Rahr-Wagner, L., Thillemann, T., Mehnert, F., Pedersen, A., & Lind, M. (2014). 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 American Journal of Sports Medicine, 42 (12), 2897-2905 DOI: 10.1177/0363546514557240