title: Osteoarthritis hip joints in Japan: involvement of acetabular dysplasia.
abstract: BACKGROUND
  We conducted a nationwide epidemiologic study regarding hip osteoarthritis (OA) in Japan, and a previous report found these patients to be unique in comparison to Caucasians. This report focused on the data regarding each hip joint, and the involvement of acetabular dysplasia with hip OA was analyzed.
  
  
  METHODS
  Seven hundred twenty OA hips were examined. Sixty-five joints with osteonecrosis of the femoral head and 215 non-OA contralateral joints of the unilateral patients were examined as controls. The revised system of stage classification for hip OA of the Japanese Orthopedic Association (JOA) was used according to the reproducibility in order to ensure reliable data from the multiple institutions. The acetabular dysplasia indexes were also chosen according to the reproducibility and measured in the radiograph of bilateral hip joints. The clinical score was assessed using the JOA scoring system. The relative risk of the grade of acetabular dysplasia indexes for hip OA was calculated as the odds ratio and the 95% confidence interval.
  
  
  RESULTS
  The stage of the OA joints deteriorated with increasing age. The clinical scores also decreased. The grade of the acetabular dysplasia indexes of the OA joints was significantly higher than that of the control joints. Each index of acetabular dysplasia demonstrated significantly increased odds ratios for hip OA. Among the OA joints, the deterioration of the OA stage was found to be significantly associated with an increasing grade of acetabular dysplasia. The odds ratio for OA deterioration in the acetabular dysplasia index was also obtained. The joints of females tended to have a higher grade and prevalence of acetabular dysplasia than those of males.
  
  
  CONCLUSIONS
  These findings confirmed a high prevalence of acetabular dysplasia in hip OA joints in Japan. Acetabular dysplasia was one of the most important factors associated with hip OA.
authors.affiliation: Department of Orthopaedic Surgery, Kyushu Rosai Hospital of Japan Labour Health and Welfare Organization, 1-3-1 Takamatsu, Kuzuhara, Kokura-minami-ku, Kitakyushu, 800-0296, Japan. jingushi.orth@kyushuh.rofuku.go.jp
authors.forename: Seiya
authors.initials: S
authors.lastname: Jingushi
authors.forename: Satoko
authors.initials: S
authors.lastname: Ohfuji
authors.forename: Muroto
authors.initials: M
authors.lastname: Sofue
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Itoman
authors.forename: Tadami
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Hamada
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Shindo
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Takatori
authors.forename: Harumoto
authors.initials: H
authors.lastname: Yamada
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yasunaga
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ito
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mori
authors.forename: Ichiro
authors.initials: I
authors.lastname: Owan
authors.forename: Genji
authors.initials: G
authors.lastname: Fujii
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Ohashi
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
authors.forename: Keita
authors.initials: K
authors.lastname: Miyanishi
authors.forename: Toshiro
authors.initials: T
authors.lastname: Iga
authors.forename: Naonobu
authors.initials: N
authors.lastname: Takahira
authors.forename: Tanzo
authors.initials: T
authors.lastname: Sugimori
authors.forename: Hajime
authors.initials: H
authors.lastname: Sugiyama
authors.forename: Kunihiko
authors.initials: K
authors.lastname: Okano
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Karita
authors.forename: Kenichi
authors.initials: K
authors.lastname: Ando
authors.forename: Takanari
authors.initials: T
authors.lastname: Hamaki
authors.forename: Teruhisa
authors.initials: T
authors.lastname: Hirayama
authors.forename: Ken
authors.initials: K
authors.lastname: Iwata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Nakasone
authors.forename: Masanori
authors.initials: M
authors.lastname: Matsuura
authors.forename: Taro
authors.initials: T
authors.lastname: Mawatari
mesh_terms: D000077:Acetabulum; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006617:Hip Dislocation / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015207:Osteoarthritis, Hip / Q000150:complications / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D017678:Sex Distribution