The Effects of Sex Steroids and Menstrual Cycle/Oestrous Phases on Knee Ligament Laxity in Humans and Rodents
January 2014
TLDR Knee laxity varies with menstrual cycle phases, being highest during ovulation and menstruation, and is influenced by sex-steroids.
The study investigated the effects of sex-steroids and menstrual cycle phases on knee ligament laxity in both rodents and humans. In rodents, ovariectomized rats treated with oestrogen and progesterone showed increased knee range of motion (ROM), while testosterone decreased it. This was linked to the up-regulation of relaxin receptor isoforms RXFP1 and RXFP2, which were antagonized by steroid hormone receptor blockers. In humans, female athletes and non-athletes exhibited significant differences in knee laxity across menstrual cycle phases, with the highest laxity during ovulatory and menstrual phases. Non-athletes had greater knee laxity compared to athletes. The study highlighted a strong correlation between knee laxity and serum relaxin levels, providing insights into the mechanisms of sex-steroid control of knee ROM and the increased susceptibility of females to non-traumatic knee injuries during certain reproductive phases.
