title: Two subtypes of radiographic osteoarthritis in the distal interphalangeal joint of the hand.
abstract: BACKGROUND
  The etiology and pathogenesis of hand osteoarthritis (OA) are not completely clarified, and several factors may cooperate in a multifactorial fashion in its development. The purpose of this study was to clarify the effects of the dominant hand that contribute to the development of distal interphalangeal (DIP) joint OA using epidemiological analyses.
  
  
  METHODS
  A total of 518 subjects (156 men, 362 women) in a rural community were analyzed. Their mean age was 63.8 years for men and 60.7 years for women. Anteroposterior (AP) standing radiographs of bilateral knees, lateral views of the lumbar spine, and AP views of bilateral hands were obtained. Furthermore, a survey of their life patterns was conducted using self-administered questionnaires. Radiographic osteoarthritis was defined as Kellgren and Lawrence grade 2 or higher. Hand OA was limited to Heberden's nodes. Generalized OA (GOA) was defined as bilateral knee OA plus lumbar spine OA.
  
  
  RESULTS
  GOA was observed in 13.0% of the subjects. The incidence of DIP joint OA was significantly higher in the GOA group than that in the non-GOA group. In the GOA group, the incidence of right-hand DIP joint OA in right-handed and left-handed subjects was 37.5% and 40.0%, respectively, without a significant difference. In the non-GOA group, however, the incidence of right-hand DIP joint OA in right-handed and left-handed subjects was 16.4% and 3.2%, respectively, with a significant difference. With a multiple logistic regression model, the P value of the handedness was marginal (0.060), but a clear tendency of increase in the odds ratio (7.129) was observed in the dominant hand for the non- GOA group. In contrast, there was no effect of the handedness on right-hand DIP joint OA in the GOA group.
  
  
  CONCLUSIONS
  There are two subtypes of hand DIP joint OA in terms of the etiology. One is environmental, and the other is genetic.
authors.affiliation: Department of Rehabilitation Medicine, Kyushu University Hospital, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Miura
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kawano
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Takasugi
authors.forename: Takashi
authors.initials: T
authors.lastname: Manabe
authors.forename: Akira
authors.initials: A
authors.lastname: Hosokawa
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D015331:Cohort Studies; D005260:Female; D005384:Finger Joint / Q000000981:diagnostic imaging* / Q000473:pathology; D007839:Functional Laterality; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000235:genetics / Q000473:pathology; D011859:Radiography