Alterations in Knee Joint Laxity During the Menstrual Cycle in Healthy Women Leads to Increases in Joint Loads During Selected Athletic Movements
Park, S-K, Stefanyshyn, D. J., Ramage, B., Hart, D.A., Ronsky, J.L.
Am J Sports Med June 2009 vol. 37 no. 6 1169-1177
Am J Sports Med June 2009 vol. 37 no. 6 1169-1177
Background: It has been speculated that the hormonal cycle may be correlated with higher incidence of ACL injury in female athletes, but results have been very contradictory.
Hypothesis: Knee joint loads are influenced by knee joint laxity (KJL) during the menstrual cycle.
Study Design: Controlled laboratory study.
Methods: Serum samples and KJL were assessed at the follicular, ovulation, and luteal phases in 26 women. Knee joint mechanics (angle, moment, and impulse) were measured and compared at the same intervals. Each of the 26 subjects had a value for knee laxity at each of the 3 phases of their cycle, and these were ordered and designated low, medium, and high for that subject.
Knee joint mechanics were then compared between low, medium, and high laxity.
Knee joint mechanics were then compared between low, medium, and high laxity.
Results: No significant differences in knee joint mechanics were found across the menstrual cycle (no phase effect). However, an increase in KJL was associated with higher knee joint loads during movement (laxity effect). A 1.3-mm increase in KJL resulted in an increase of approximately 30% in adduction impulse in a cutting maneuver, an increase of approximately 20% in knee adduction moment, and a 20% to 45% increase in external rotation loads during a jumping and stopping task
Conclusion: Changes in KJL during the menstrual cycle do change knee joint loading during movements. It was found that increased KJL during the menstrual cycle leads to greater knee joint loads in selected high-risk movements in healthy young women. It was also found that the influence of hormones on KJL was subject specific, possibly explaining why some female athletes are more prone to ACL injuries than others. As a significant relationship exists between KJL and knee joint loads in female athletes, it will be necessary to apply the findings to more practical situations as a way of reducing ACL injury rates for female athletes.
Clinical Relevance: Our findings will be beneficial for researchers in the development of more effective ACL injury prevention programs.
Keywords: knee joint laxity (KJL); menstrual cycle; knee joint loads; ACL injury
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