Incidental Rotator Cuff Abnormalities on Magnetic Resonance Imaging.

Importance: Shoulder pain is a common musculoskeletal complaint often attributed to rotator cuff (RC) abnormalities. Diagnostic imaging is frequently used, but the association between RC abnormalities and shoulder symptoms remains uncertain. Objective: To determine the prevalence of RC abnormalities in a general population sample and their association with shoulder symptoms. Design, Setting, and Participants: Population-based cross-sectional study in a nationally representative random sample of adults aged 41 to 76 years who underwent standardized clinical assessment and bilateral 3-Tesla magnetic resonance imaging (MRI) of the shoulders conducted from February 2023 to April 2024 in Finland. Eligibility criteria included ability to undergo MRI and absence of previous shoulder replacement surgery. Exposures: Structured interviews, standardized questionnaires, clinical shoulder tests, and shoulder MRI. Main Outcomes and Measures: RC tendon status was classified on MRI as normal, tendinopathic, partial-thickness tear (PTT), or full-thickness tear (FTT). Shoulder symptoms were defined as pain or dysfunction in the preceding week. The prevalence of RC abnormalities was compared across age groups and between symptomatic and asymptomatic shoulders, adjusting for demographic factors, concurrent MRI findings, and clinical examination. Results: Among 602 participants (median age, 58 [range, 41-76] years; 52% female), RC abnormalities on MRI were found in 595 (98.7%; 95% CI, 97.5%-99.5%): 25% tendinopathy, 62% PTT, and 11% FTT. The prevalence and severity of abnormalities increased with age but did not differ between sexes. RC abnormalities were present in 96% of asymptomatic shoulders (1039 of 1076) and 98% of symptomatic shoulders (126 of 128). Only FTTs were more prevalent in symptomatic shoulders (14.6%) than in asymptomatic shoulders (6.5%), but this difference diminished after adjustment (absolute difference, 0.8%; 95% CI, -3.4% to 6.0%). Conclusions and Relevance: In this population-based study, RC abnormalities were nearly universal after age 40 years and showed poor concordance with shoulder symptoms. These findings suggest that RC abnormalities often represent normal age-related changes rather than disease and call into question the clinical value of routine imaging for atraumatic shoulder pain.