Background Increased prevalence of knee osteoarthritis (OA) among postmenopausal women suggests involvement of endogenous hormones in pathogenesis. However, the effects of endogenous sex hormones on knee OA structures remain uncertain.
Objectives To describe the longitudinal associations between serum levels of estrogen, progesterone and testosterone and knee structural changes using magnetic resonance imaging (MRI) in both males and females with symptomatic knee OA.
Methods We examined 200 participants (mean age 63.0 ± 7.3 years) from a clinical trial of vitamin D supplement for symptomatic knee OA. Serum levels of estradiol, progesterone, testosterone and sex hormone binding globulin (SHBG) were analyzed at baseline and 24 months later. Magnetic resonance imaging (MRI) scans of the knees were obtained at both baseline and follow-up for the measurement of cartilage volume, cartilage defects, bone marrow lesions (BMLs) and effusion-synovitis volume. Knee pain was assessed using a 100mm visual analogue scale (VAS). Longitudinal data were analyzed using linear mixed-effects model.
Results 107 males and 93 females were included in this study. For females, after adjustment for age, body mass index, and treatment allocation, progesterone was associated with cartilage volume (β =0.12 per quartile, p=0.01). Estradiol levels were associated with lower grades of BMLs (β = -0.45 per quartile, p=0.03), while estradiol (β = -1.26 per quartile, p=0.05), progesterone (β = -1.60 per quartile, p<0.01) and testosterone (β = -1.49 per quartile, p=0.02) were inversely associated with effusion-synovitis volume for females. No consistent associations were observed for males.
Conclusions Endogenous estradiol, progesterone and testosterone may be protective for joint structural changes in women but not men. This may contribute to observed sex differences in knee OA.
Acknowledgement Jodi Barling, Kay Nguo, Judy Hankin and Alice Noone have been involved in the coordination of this study. Rob Warren measured knee cartilage volume.
Disclosure of Interest None declared