Testosterone levels and risk of adhesive capsulitis: a 1:1 propensity matched analysis

Adhesive capsulitis, commonly known as frozen shoulder, is a fibro-inflammatory condition characterized by the gradual onset of pain and progressive restriction of shoulder motion, with evidence suggesting that endocrine factors may play a role in its pathogenesis. Despite biologic plausibility linking testosterone to capsular fibrosis, the relationship between endogenous androgen levels and adhesive capsulitis has not been thoroughly investigated. The purpose of this study is to assess the risk of developing adhesive capsulitis within 1 year, 2 years, and 5 years after their serum testosterone level lab draw. A retrospective cohort study was conducted using the TriNetX research database to identify male patients aged 35 years and older who had testosterone lab levels between 2005 and 2025 and never had any surgical procedures on the shoulder. Patients were stratified into 2 cohorts based on serum testosterone levels: a low testosterone group (serum testosterone levels <300 ng/dL) and a normal to high-range group (serum testosterone levels 300-1,000 ng/dL). Sub-analyses were performed based on excluding and including patients receiving testosterone replacement therapy. Risk ratios (RRs), confidence intervals (CIs), and P-values were calculated using Student's t-tests and chi-square tests, as appropriate. After propensity score matching, 301,219 patients were included in each testosterone cohort. Patients with normal-high testosterone levels had a significantly greater risk of adhesive capsulitis compared with those with low testosterone at 1 year (0.17% vs. 0.14%, RR = 1.23, 95% CI 1.08-1.39, P = .002), 2 years (0.29% vs. 0.25%, RR = 1.17, 95% CI 1.06-1.29, P = .002), and 5 years (0.54% vs. 0.48%, RR = 1.12, 95% CI 1.05-1.21, P = .001) from their lab draw. When excluding men on testosterone replacement therapy, results remained consistent across all time points-1 year (0.15% vs. 0.12%, RR = 1.23, 95% CI 1.03-1.47, P = .022), 2 years (0.26% vs. 0.22%, RR = 1.17, 95% CI 1.03-1.34, P = .019), and 5 years (0.47% vs. 0.42%, RR = 1.13, 95% CI 1.03-1.25, P = .013). Among patients on testosterone replacement therapy, no significant differences were observed at 1 year (0.19% vs. 0.16%, RR = 1.18, 95% CI 0.97-1.45, P = .106) or 2 years (0.35% vs. 0.30%, RR = 1.15, 95% CI 0.99-1.34, P = .061), although risk was significantly elevated at 5 years (0.67% vs. 0.59%, RR = 1.15, 95% CI 1.03-1.28, P = .010). Normal-high endogenous testosterone levels (300-1,000 ng/dl) were associated with an increased risk of adhesive capsulitis. These findings highlight the importance of considering hormonal status in adhesive capsulitis risk assessment, and prospective studies with direct hormone measurements are warranted to validate these associations.