title: High prevalence of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease.
abstract: BACKGROUND
  Acetabular retroversion is observed in hips after various pediatric hip diseases. This study sought to examine the frequency of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease and its correlation with the prominence of the ischial spine.
  
  
  METHODS
  We retrospectively investigated the version and morphological features of the acetabulum using pelvic radiographs after Legg-Calvé-Perthes disease (107 affected hips treated non-operatively and 72 unaffected hips from the contralateral side). The diagnosis of acetabular retroversion was made based on the presence of a positive cross-over sign on anteroposterior pelvic radiographs. The correlation between the presence of a positive cross-over sign and modified Stulberg classes, the onset age of Legg-Calvé-Perthes disease, radiographic parameters for acetabular dysplasia and the prominence of the ischial spine were examined.
  
  
  RESULTS
  The prevalence of a positive cross-over sign was 49.5 % (45 of 91 hips) in affected hips and 45.8 % (33 of 72 hips) in unaffected hips. Hips with a positive cross-over sign were significantly coexistent bilaterally. The prevalence of prominence of the ischial spine in the positive cross-over sign group was 71.4 % in the affected side and 81.8 % in the unaffected side, indicating a significant correlation between the cross-over sign and the prominence of the ischial spine in both affected and unaffected hips. The positive cross-over sign did not have any correlation with the parameters for acetabular dysplasia and the onset age, however, had a significant correlation with the severity of the femoral head deformity.
  
  
  CONCLUSIONS
  High prevalence of acetabular retroversion in both affected and unaffected hips after Legg-Calvé-Perthes disease was demonstrated. Symmetric acetabular deformity and the coexistence of prominence of the ischial spine suggested the effects of the Legg-Calvé-Perthes disease lesions on the skeletal development of the whole pelvis. Further follow-up is needed to clarify the pathological significance of acetabular retroversion after Legg-Calvé-Perthes disease.
authors.affiliation: Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Kawahara
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Oketani
authors.forename: Akifusa
authors.initials: A
authors.lastname: Wada
authors.forename: Masanori
authors.initials: M
authors.lastname: Fujii
authors.forename: Takuaki
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Taro
authors.initials: T
authors.lastname: Mawatari
authors.forename: Goro
authors.initials: G
authors.lastname: Motomura
authors.forename: Taishi
authors.initials: T
authors.lastname: Sato
authors.forename: Mio
authors.initials: M
authors.lastname: Akiyama
authors.forename: Toshio
authors.initials: T
authors.lastname: Fujii
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Takamura
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000077:Acetabulum; D060751:Bone Retroversion / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000209:etiology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007873:Legg-Calve-Perthes Disease / Q000150:complications*; D008297:Male; D015995:Prevalence; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index