Pubertal Timing is Not Related to Anterior Cruciate Ligament Laxity in Young Adults.

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Females sustain ACL injuries more often than males, especially among physically active adolescents and young adults. Studies suggest that increased estrogen during the ovulatory phase of the menstrual cycle is related to ephemeral increases in ACL laxity, and thus elevated injury risk. These hormonal factors may partially explain the sex-bias in injury risk, since males do not experience the same estrogen spikes and thus avoid these bouts of elevated risk. Little is known, however, about how variability in estrogen exposure within females affects inter-individual differences in injury risk. One factor that may play a role in cumulative estrogen exposure is age at menarche, since it relates to total number of cycles experienced. Our prior work shows links between age at menarche, pubertal growth patterns, and biomechanical risk for ACL injury. It is possible that age at menarche also has an impact on ACL injury risk through effects on laxity.

PURPOSE: To determine if age at menarche is related to female ACL laxity.

METHODS: Subjects were recreationally active undergraduate and medical school females (N=15) and males (N=20). Males served as a control group, in which pubertal development timing was assessed as age at achieving adult height (recall). Age at menarche and current menstrual status in females were assessed by recall questionnaire. Telos™ stress radiography was used to assess ACL laxity. Statistical analysis consisted of an independent samples t-test to compare laxity in males and females. Linear regression analysis was used to determine whether laxity was related to pubertal timing within each sex.

RESULTS: The t-test found no significant sex difference in ACL laxity (female mean ± SD = 3.0 ± 1.8 mm; male mean ± SD = 3.7 ± 1.7 mm; P = 0.26). In males, regression analysis demonstrated no relationship between age at achieving adult height and knee laxity: slope = -0.03 (95% CI: -0.38 – 0.31); intercept = 4.34 (95% CI: -1.60 – 10.39); r2 = 0.003; P = 0.83. Similarly, females exhibited no relationship between knee laxity and age at menarche: slope = -0.17 (95% CI: -0.95 – 0.61); intercept = 5.15 (95% CI: -4.87 – 15.16); r2 = 0.02; P = 0.65. The absence of regression relationship persisted after controlling for current menstrual cycle status.

CONCLUSION: ACL laxity in females appears to be unrelated to age at menarche.