Sex hormones in association with general joint laxity and hypermobility in the temporomandibular joint in adolescents-results of the epidemiologic LIFE child study

Objectives The aim of this cross-sectional study was to investigate whether sex hormones (testosterone, oestradiol, sex-hormone-binding globulin = SHBG) are associated with general joint laxity (GJL) and hypermobility or derangements of the temporomandibular joint (TMJ) in adolescents. Methods Within the LIFE Child study, 970 adolescents (10-18 years) were included. GJL was assessed using the Beighton test. Maximum mouth opening (MMO) and clinical clicking sounds as signs of disc displacement (DD) in the TMJ were assessed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Serum levels of sex hormones were assessed using standardised laboratory analyses. Results Hypermobile joints were found in 54.9% (N = 532) of the sample; females were more affected than males (61.4% vs. 51.8%, P < 0.001). Using logistic regression analyses, the odds ratio (OR) for having >1 hypermobile joints increased to 1.15 (95% confidence interval [CI]: 1.04-1.27) in males and 1.09 (95% CI: 1.02-1.17) in females per 10 units of the SHBG serum level, compared to those without hypermobile joints-after controlling for the effect of age, adjusted BMI, pubertal development (Tanner scale), testosterone as well as oestradiol levels. Female subjects with >1 hypermobile joints showed a higher OR (1.89; 95% CI: 1.05-3.43) for having clinical clicking sounds in the TMJ and a 3.28 times higher OR (95% CI: 1.44-7.44) for MMO >= 55 mm. Conclusions We observed age- and gender-independent associations of higher SHBG serum levels with GJL in adolescents. Moreover, hypermobile female adolescents show a more frequent hypermobility of the TMJ and clinical signs of DD.