title: Factors associated with radiographic osteoarthritis of the knee among community-dwelling Japanese women: the Hizen-Oshima Study.
abstract: BACKGROUND
  Osteoarthritis (OA) of the knee is the most common form of arthritis and is a major contributor to functional impairment and reduced independence in older adults. In Japan, knee OA is a frequent cause of pain and disability, but few epidemiological studies have examined the demographic or lifestyle factors that influence OA of the knee. We examine the risk factors for OA of the knee among Japanese community-dwelling women aged 40-89 years (mean age 64.2, SD 9.6 years).
  
  
  METHODS
  Anteroposterior weight-bearing knee radiographs were graded according to the criteria described by Kellgren-Lawrence (K/L). We defined knee OA as a K/L grade of 2 or higher (using a 0-4 scale) based on the plain radiographs. History of knee injury, type of occupation, and daily intake of antioxidant nutrients including vitamin C and carotene were obtained from questionnaires.
  
  
  RESULTS
  Among the 582 subjects, 195 women (33.5%) suffered from knee OA. Logistic regression analysis showed that older age [odds ratio (OR) 1.8, 95% confidence interval (95% CI) 1.6-2.1 per 5-year increase], higher body mass index (OR 2.2, 95% CI 1.7-3.0 per 5-unit increase) and previous knee injury (OR 3.1, 95% CI 1.7-5.6) were associated with knee OA. The occupation of farming and intake of antioxidant nutrients were not associated with knee OA.
  
  
  CONCLUSIONS
  Older age, obesity and previous knee injury represent independent risk factors for knee OA among Japanese women.
authors.affiliation: Department of Orthopaedic Surgery, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, 852-8501, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hashikawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Osaki
authors.forename: Zhaojia
authors.initials: Z
authors.lastname: Ye
authors.forename: Masato
authors.initials: M
authors.lastname: Tomita
authors.forename: Yasuyo
authors.initials: Y
authors.lastname: Abe
authors.forename: Sumihisa
authors.initials: S
authors.lastname: Honda
authors.forename: Noboru
authors.initials: N
authors.lastname: Takamura
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shindo
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Aoyagi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000453:epidemiology; D015995:Prevalence; D011446:Prospective Studies; D011859:Radiography; D012307:Risk Factors; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D016474:Weight-Bearing