title: The prevalence of acetabular retroversion among various disorders of the hip.
abstract: BACKGROUND
  Acetabular retroversion can result from posterior wall deficiency in an otherwise normally oriented acetabulum or from excessive anterior coverage secondary to a malpositioned acetabulum, or both. Theoretically, a retroverted acetabulum, which adversely affects load transmission across the hip, may occur more frequently in hips with degenerative arthritis. The aim of this study was to assess the prevalence of acetabular retroversion in normal hips and in hips with osteoarthritis, developmental dysplasia, osteonecrosis, and Legg-Calvé-Perthes disease.
  
  
  METHODS
  We retrospectively examined anteroposterior radiographs of the pelvis of 250 patients (342 hips). Fifty-six patients (112 hips) had normal findings; sixty-six patients (seventy hips) had osteoarthritis; sixty-four (seventy-four hips), developmental dysplasia; thirty (thirty-six hips), osteonecrosis of the femoral head; and thirty-four (fifty hips), Legg-Calvé-Perthes disease. The sole criterion for a diagnosis of acetabular retroversion was the presence of a so-called cross-over sign on the anteroposterior radiograph of the pelvis.
  
  
  RESULTS
  The prevalence of acetabular retroversion was 6% (seven of 112 hips) in the normal group, 20% (fourteen of seventy hips) in the osteoarthritis group, 18% (thirteen of seventy-four hips) in the developmental dysplasia group, 6% (two of thirty-six hips) in the group with osteonecrosis of the femoral head, and 42% (twenty-one of fifty hips) in the group with Legg-Calvé-Perthes disease. In patients with Legg-Calvé-Perthes disease, the prevalence of acetabular retroversion was 68% in twenty-five hips with Stulberg class-III, IV, or V involvement. In contrast, only four (16%) of twenty-five hips with Stulberg class-I or II involvement had acetabular retroversion. The difference was significant (p = 0.0002). Patients with osteoarthritis, developmental dysplasia, or Legg-Calvé-Perthes disease are significantly more likely to have acetabular retroversion than are normal subjects (p < 0.05).
  
  
  CONCLUSIONS
  Acetabular retroversion occurs more commonly in association with a variety of hip diseases, in which the prevalence of subsequent degenerative arthritis is increased, than has been previously noted.
authors.affiliation: Department of Orthopaedic Surgery, Fukuoka University School of Medicine, 7-45-1 Nanakuma, Jyonan-ku, Fukuoka 814-0180, Japan. md010001@mms.bbiq.jp
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Ezoe
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Naito
authors.forename: Toshio
authors.initials: T
authors.lastname: Inoue
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D000293:Adolescent; D000328:Adult; D001847:Bone Diseases / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology; D005271:Femur Head Necrosis / Q000150:complications; D006615:Hip; D006801:Humans; D007592:Joint Diseases / Q000150:complications*; D008875:Middle Aged; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies