Genetic and environmental influences on rotator cuff tears: a population-based twin study

Abstract Background Rotator cuff tear (RCT) is a leading cause of shoulder pain, disability, and healthcare utilization worldwide, imposing notable individual and societal burden. Despite its high prevalence and impact on quality of life and healthcare costs, the contribution of inherited susceptibility to clinically manifest RCT remains unclear. Methods We conducted a nationwide, population-based twin study by linking the Danish Twin Registry with the Danish National Patient Registry, including all monozygotic (MZ) and dizygotic (DZ) twin pairs born 1940–1980 and alive on January 1st, 1980. RCT cases between 1994 and 2014 were identified using relevant ICD-8 and ICD-10 codes. Cumulative incidence of receiving an RCT diagnosis was estimated, and familial aggregation was assessed using casewise concordance. Genetic and environmental contributions to liability were quantified using biometric twin models. Results By age 70, the population-based cumulative incidence of RCT was higher in men (6.5%, 95% CI: 6.0%–7.2%) than in women (3.8%, 95% CI: 3.4%–4.3%). The risk of RCT in a twin given RCT in the co-twin was generally higher in MZ than in DZ twins overall, most clearly among men, indicating familial aggregation consistent with genetic effects. In the full cohort, the preferred biometric model (AE) indicated that approximately half the variance in liability to RCT was attributable to additive genetic effects ( heritability : a 2 = 0.49, 95% CI: 0.27–0.70), with the remainder due to unique environmental effects ( e 2 = 0.51, 95% CI: 0.30–0.73). Sex-stratified analyses suggested a stronger genetic contribution among men, whereas estimates among women were less precise. Conclusions These findings support clinically diagnosed rotator cuff tear as a common, partially heritable musculoskeletal disorder and highlight the importance of considering individual susceptibility alongside occupational and environmental exposures in prevention, with implications for population-level risk assessment and clinical management.