title: Absolute serum hormone levels predict the magnitude of change in anterior knee laxity across the menstrual cycle.
abstract: This study aimed to determine whether absolute sex hormone concentrations predict the magnitude of knee joint laxity changes across the menstrual cycle. Twenty-two females (18-30 years, body mass index <or=30), who reported normal menstrual cycles for the previous 6 months were tested daily across one complete menstrual cycle for serum levels of estradiol (E=pg/mL), progesterone (P=ng/mL), and testosterone (T=ng/dL), and knee joint laxity (K(Lax)=mm displacement at 134N) measured with a standard knee arthrometer. The change in K(Lax) across the cycle (maximum-minimum), and minimum (early follicular) and peak (postovulatory) hormone concentrations were recorded for each subject. A stepwise linear regression determined if the minimum, peak, or absolute change in hormone concentrations would predict the magnitude of change in K(Lax) across the cycle. K(Lax) changed on average 3.2+/-1.1 mm across the menstrual cycle (range, 1.5-5.3 mm). Minimum levels of E (39.9+/-11.8 pg/mL) and P (0.61+/-0.27 ng/mL), coupled with peak concentrations of E (199.6+/-54.9 pg/mL) and T (22.5+/-10.5 ng/dL) explained 57.6% of the change in K(Lax) across the cycle. Greater absolute changes in K(Lax) were observed in response to peak E and T levels when minimum E concentrations were lower and minimum P concentrations were higher in the early follicular phase. The absolute minimum concentrations of E and P in the early follicular phase appear to be important factors in determining the sensitivity of the knee joint's response to changing hormone levels.
authors.affiliation: Applied Neuromechanics Research Laboratory, The University of North Carolina at Greensboro, 237B HHP Building, Greensboro, NC 27402, USA. sjshultz@uncg.edu
authors.forename: Sandra J
authors.initials: SJ
authors.lastname: Shultz
authors.forename: Bruce M
authors.initials: BM
authors.lastname: Gansneder
authors.forename: Todd C
authors.initials: TC
authors.lastname: Sander
authors.forename: Susan E
authors.initials: SE
authors.lastname: Kirk
authors.forename: David H
authors.initials: DH
authors.lastname: Perrin
mesh_terms: D000293:Adolescent; D000328:Adult; D004958:Estradiol / Q000097:blood*; D005260:Female; D005544:Forecasting; D006801:Humans; D007593:Joint Instability / Q000175:diagnosis*; D007719:Knee Joint / Q000502:physiology*; D008597:Menstrual Cycle / Q000097:blood / Q000502:physiology*; D011374:Progesterone / Q000097:blood*; D016059:Range of Motion, Articular / Q000502:physiology; D013739:Testosterone / Q000097:blood*
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol