ACL Injury and the Menstrual Cycle

June 27, 2011

This article was written for my Exercise Physiology class while I was in college as a research paper. It is the start of a new series of articles you’ll start to find here. I plan to write more about athletic and orthopedic injuries in the near future. Expect to see a couple more ACL articles in the next week or so.

Over the past several years, athletic participation by female athletes has skyrocketed and there has been a coinciding increase in injury to the anterior cruciate ligament (ACL). Myer, Ford, and Hewett claim that female athletes are at a 4-to-6-fold increased risk for ACL injury than male athletes who participate at a similar level in a similar sport or activity. There are many factors as to why this would be true and there are probably factors that have not been fully considered as of yet. One of these potential factors is the menstrual cycle and its fluctuation of hormones in the female body causing possible laxity of the ACL as well as other ligaments. The intent of this paper is to explore research that examines how
the menstrual cycle may influence ACL injury rates.

Researchers in one study looked at 37 patients and found that 25 had injured their ACL during the follicular phase and 11 of the 37 had an injury during the luteal phase (Slauterbeck, Fuzie, Smith, Clark, Xu, Starch, and Hardy; 2002). Beynnon and Shultz (2008) reported another study that found ACL injury incidences occurring more during days 9-14 of the menstrual cycle than after day 15. This would appear to agree with Slauterbeck et al (2002) that females are more likely to suffer injury near the beginning of the cycle rather than near the end. Their findings that ACL injury occurred most often on days 1 and 2 of menses which led them to believe that it was not coincidence but rather a matter of an effect by hormones on the joint (Slauterbeck et al, 2002).

A study conducted by Van Lunen, Roberts, Branch, and Dowling (2003) did not agree with the above conclusions that the status of the menstrual cycle has any affect on the potential for ACL injury. In this study, the authors used a KT-2000 machine and radiographic measurements to measure the laxity of the ACL during the various phases of the menstrual cycle (Van Lunen et al, 2003). While the authors acknowledge that certain hormones have an effect on the makeup of the ACL, they are not so certain that those hormones contribute to ligament laxity changes (Van Lunen et al, 2003). Beynnon and Shultz (2008) assert in their summary that the most common belief right now is that the hormones must have some involvement because they wrote that the risk of ACL injury is not identical throughout the cycle. This is consistent with the findings of Slauterbeck et al that there is some connection to the hormonal status of an athlete and her risk for injury with the ACL. Unfortunately, there is no sort of conditioning program that can work to decrease the likelihood of this factor coming into play so right now the only answer that appears to be preventing such injury from occurring due to hormonal influences would be to disallow those athletes from participation during the first part of the menstrual cycle. This would definitely cause multiple other issues beyond the scope of this article.

A case report followed a young female athlete for three years before she suffered an ACL injury. After her injury, it was discovered during an interview that the athlete had missed three consecutive menstrual cycles which could have led to an increase in her risk of injury (Myer, Ford, Divine, Wall, Hahanov, and Hewett, 2009). The authors of the case study briefly discuss the hormonal influences on how the joints are controlled which could be a factor in ACL injuries in females. They go on to say that estrogen is a significant aspect of muscle function as well as tendon and ligament strength (Myer et al, 2009).

More research is definitely needed to explore even more about the causes of ACL injury in female athletes if the medical community wants to fully understand the injury and discover possible techniques or methods to prevent and overcome the root causes of injury. Also, it is possible that the menstrual cycle may not have a large affect on the laxity of the ACL, but instead involve other structures and cause potential weakness in surrounding soft tissue structures that are important to the stabilization of the tibia. This would be consistent with the various studies that have been mentioned in this article. Slauterbeck et al (2002) did not specifically examine the ligament itself but rather the authors looked more at the time of incidence and how that time coincided with the period of the subject’s menstrual cycle. There is a long way to go for the medical community to find all the answers as to how prevention of ACL injury among females can be optimized to the fullest extent. The most likely answer is that there is no cure all but that each athlete must weigh the risks and understand that female athletes are more likely to suffer an ACL injury than male counterparts.

References

Myer, Gregory D., Ford, Kevin R., & Hewett, Timothy E. (2004). Rationale and clinical techniques for anterior cruciate ligament injury prevention among female athletes. Journal of Athletic Training. 39 (4), 352-364.

Myer, Gregory D., Ford, Kevin R., Divine, Jon G., Wall, Eric J., Kahanov, Leamor, & Hewett, Timothy E. (2009). Longitudinal assessment of noncontact anterior cruciate ligament injury risk factors during maturation in a female athlete: A case report. Journal of Athletic Training, 44(1), 101-109.

Slauterbeck, James R., Fuzie, Stephen F., Smith, Michael P., Clark, Russell J., Xu, K. Tom, & Starch, David W., Hardy, Daniel M. (2002). The menstrual cycle, sex hormones, and anterior cruciate ligament injury. Journal of Athletic Training. 37(3), 275-280.

Van Lunen, Bonnie L., Roberts, John, Branch, J. David, & Dowling, Elizabeth A. (2003). Association of menstrual-cycle hormone changes in anterior cruciate ligament laxity measurements. Journal of Athletic Training, 38(4), 298-303.

Beynnon, Bruce D., & Shultz, Sandra J. (2008). Anatomic alignment, menstrual cycle phase, and the risk of anterior cruciate ligament injury. Journal of Athletic Training. 43(5), 541-542.

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