Women’s Health
Lower estradiol concentrations are associated with knee-specific pain in postmenopausal women Emily Ha* Emily Ha Jennifer Brooks Peter M Smith Andy Kin On Wong
Background: Knee osteoarthritis is a major source of knee pain in postmenopausal women, and evidence suggests a link between sex hormones and chronic pain. However, the relationship between estrogen concentrations and the development of knee pain in postmenopausal women is underexplored. The study aimed to determine the cross-sectional and longitudinal associations between estradiol concentration and knee pain in postmenopausal women.
Methods: Data on postmenopausal women in the United Kingdom (UK) Biobank were used. Baseline serum estradiol (E2) was measured using a two-step competitive assay (range: 73–17,621 pmol/L). For 155,341 out of 192,532 postmenopausal women, estradiol concentrations were below the detection limit. Thus, quantifiable estradiol was categorized into tertiles, with an additional undetectable category. Knee pain was measured via questionnaires at baseline and the five-year follow-up. Modified Poisson models, adjusted for potential confounders, were used to estimate the cross-sectional and longitudinal associations.
Results: Among 192,532 postmenopausal women (mean age=60.4, SD=5.4), 16.4% reported knee pain and the median estradiol concentration was 289.0 pmol/L (IQR=217.0 pmol/L–443.8 pmol/L). Those with lower estradiol concentrations had a significantly higher risk of knee pain at baseline and 5 years later (18–28% higher risk) compared to the highest tertile. Postmenopausal women with undetectable concentrations had 1.18 times the prevalence of knee pain at baseline (95% CI=1.10–1.27) and 1.87 times the risk of knee pain 5 years later (95% CI=1.70–1.95) compared to the highest estradiol tertile.
Discussion/Conclusion: Lower estradiol concentrations were significantly associated with an increased risk for knee pain in postmenopausal women. Estradiol may play a role on influencing the degree of knee pain. Specific mechanisms of how low estradiol levels could translate to more knee pain should be investigated as future mitigation strategies.