The prevalence of shoulder osteoarthritis in the elderly Korean population: association with risk factors and function.

Background: The purpose of this study was to document the prevalence of shoulder osteoarthritis (OA) in the elderly population in South Korea, to determine the risk factors for shoulder OA, and to evaluate the relationship with function.

Materials And Methods: This project was part of a population-based prospective cohort study of health, aging, and common geriatric diseases in the elderly population of the authors' area of Seongnam. A total of 1118 residents were randomly invited, and 679 participated. The mean age of respondents was 71.8 ± 5.7 years (range, 65-97 years), and 396 (58.3%) were women. Bilateral shoulder radiographs were taken, and the grade of OA was evaluated using the Samilson-Prieto method. Functional status was evaluated using the Disabilities of Arm, Shoulder and Hand (DASH) instrument.

Results: Radiographic primary shoulder OA was detected in 109 people (16.1%), and secondary OA in 9 (1.3%). There were 77 shoulders of grade 1 (11.3%), 23 of grade 2 (3.4%), and 9 of grade 3 (1.3%). The risk of shoulder OA increased according to age, with odds ratio (OR) of 2.20 in patients aged 70 to 74 years (P = .004) and 3.42 in patients aged 75 years and older (P < .001). Knee OA was also a significant risk factor for shoulder OA (OR, 1.96; P = .002). The DASH score was significantly higher in the OA group and increased according to the grade of shoulder OA (P < .001).

Conclusion: Primary shoulder OA is not as rare as previously reported. Our data also demonstrated that older age and knee OA were determining risk factors for shoulder OA, and shoulder OA was related to poor function.