The Menstrual Cycle and Anterior Cruciate Ligament Injury Risk

Abstract

The menstrual cycle and associated hormonal fluctuations are considered risk factors for non-contact anterior cruciate ligament (ACL) injuries in female athletes. Researchers have used a 'normal' 28-day cycle and relied upon menstrual history questionnaires or a biological sample (i.e. blood, saliva) taken on a single day to identify the phase of the menstrual cycle where an ACL tear has occurred. However, evidence from available studies lack adequate consideration of menstrual cycle variability that exists in the general population and neglect to acknowledge the greater prevalence of subtle menstrual disturbances in physically active and athletic women. Inter- and intra-woman menstrual cycle variability is large for total cycle, follicular phase and luteal phase length ranging from 22 to 36, 9 to 23 and 8 to 17 days, respectively (95% CI). More importantly, subtle menstrual disturbances such as anovulation and luteal phase defects are common in athletic women with a high prevalence of cycle-to-cycle variations. To complicate matters further, menstrual history questionnaires inaccurately quantify cycle length compared with prospective monitoring of cycle length, highlighting the need to implement more sophisticated methods for identifying menstrual cycle/phase characteristics. Regardless of variability and/or the presence of subtle menstrual disturbances, women may still have regularly occurring menses, making it extremely difficult to accurately identify the phase of the menstrual cycle where an ACL tear has occurred based on a menstrual history questionnaire or a single biological sample. Therefore, the assumption that normal ovarian endocrine function is synonymous with regularly occurring menses in physically active and athletic women is unjustified. Thus, definitive conclusions are not warranted regarding the association between the menstrual cycle and non-contact ACL injury risk based on currently available data. Future work in this area must incorporate methods to prospectively evaluate and accurately characterize menstrual cycle characteristics if we are to link the hormonal fluctuations of the menstrual cycle to non-contact ACL injury risk.

Applied Physiology of Female Soccer: An Update

“…A full appraisal of these topics is beyond the scope of this review and in some instances has already been conducted [71][72][73][74][75][76]. However, the importance of these variables to female soccer players and the potential impact on training, performance and injury risk should not be underestimated.…”

ACL Research Retreat VII: An Update on Anterior Cruciate Ligament Injury Risk Factor Identification, Screening, and Prevention

“…Investigations should (1) verify the phases of the cycle (or desired hormone environment) with actual hormone measurements (considering relevant hormones to include estrogen, progesterone, and possibly others) rather than relying on calendar day of the cycle 214 and (2) obtain multiple hormone samples over repeated days to better characterize hormone profiles within a given female. 215,216 This may be particularly important when documenting relaxin exposure. Because relaxin rises and peaks during a relatively short window (6-10 days) after ovulation based on other hormonal events, [217][218][219][220] we do not know if the high proportion of undetectable levels within a single sample (as high as 64%-80%) [221][222][223][224] is due to timing or suggests that only a subset of females are exposed to appreciable relaxin levels due to mediating factors.…”

“…Menstrual dysfunction in exercising females may be more prevalent than originally thought (up to 50% in exercising females). 216,226,227 Thus, the effects of menstrual disturbances on injury risk potential are poorly understood. 7.…”

A collaborative and comprehensive approach to women’s musculoskeletal health

“…11 Sex disparity in MSK injury are likely due to a combination of factors, such as sex differences in anatomy, motor control, and sex hormones. [12][13][14][15][16] Women are more likely to have a narrow intercondylar notch, which makes them more prone to ACL injury. 17,18 It has also been hypothesized that the reproductive hormone estrogen may bind to specific receptors on fibroblasts in the ACL, leading to decreased production of collagen.…”