title: The prevalence of shoulder osteoarthritis in the elderly Korean population: association with risk factors and function.
abstract: 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.
  
  
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Korea.
authors.forename: Joo Han
authors.initials: JH
authors.lastname: Oh
authors.forename: Seok Won
authors.initials: SW
authors.lastname: Chung
authors.forename: Chung Hee
authors.initials: CH
authors.lastname: Oh
authors.forename: Sae Hoon
authors.initials: SH
authors.lastname: Kim
authors.forename: Sang Jae
authors.initials: SJ
authors.lastname: Park
authors.forename: Ki Woong
authors.initials: KW
authors.lastname: Kim
authors.forename: Joon Hyuk
authors.initials: JH
authors.lastname: Park
authors.forename: Seok Bum
authors.initials: SB
authors.lastname: Lee
authors.forename: Jung Jae
authors.initials: JJ
authors.lastname: Lee
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D010003:Osteoarthritis / Q000453:epidemiology* / Q000503:physiopathology; D015995:Prevalence; D011379:Prognosis; D011446:Prospective Studies; D016059:Range of Motion, Articular; D056910:Republic of Korea / Q000453:epidemiology; D012785:Shoulder Joint / Q000503:physiopathology*