Effects of Urinary Sex Hormones during the Menstrual Cycle on Anterior Cruciate Ligament Laxity in Female Adolescent Soccer Players
(Yipei He, Dongliang Shi, Bingyin Liang, Rong Su, Xian Zhang, Li Cui, Han Meng, Yinan Shi, Yan Qi)

The aim of this study was to investigate the relationship between urinary sex hormone levels and anterior cruciate ligament (ACL) laxity in female adolescent soccer players, and to explain the relationship through establishing regression equations. Urinary aliquots were collected daily from 15 healthy subjects over a continuous period of 27–34 days. Knee laxity at 67, 89 and 133 N was assessed using a standard KT-1000 knee arthrometer. Urinary metabolite levels of estradiol, progesterone and testosterone were tested using UPLC-Xevo TQ MS. Greatest ACL laxity was recorded during the luteal phase, followed by ovulatory and follicular phases (p < 0.05). In addition, there were significant correlations between ACL laxity and estradiol or progesterone (p < 0.05). Estradiol, progesterone, and their interaction in the model were significant predictors of knee laxity (p < 0.05). In conclusion, ACL laxity was significantly and positively correlated with urinary estradiol and progesterone levels. The menstrual cycle (especially during the luteal phase) had a significant effect on ACL laxity. The regression equations we developed to analyze female adolescent soccer players accounted for 7.39% of the variation in ACL laxity with urinary sex hormones.