title: Acetabular tilt correlates with acetabular version and coverage in hip dysplasia.
abstract: BACKGROUND
  The rotational position of the acetabulum to the pelvis (acetabular tilt) may influence acetabular version and coverage of the femoral head. To date, the pathologic significance of acetabular tilt in hip dysplasia is unknown.
  
  
  OBJECTIVE
  We determined whether acetabular tilt in hip dysplasia is different from that in normal hips and whether this correlates with acetabular version and coverage.
  
  
  METHODS
  We measured the acetabular tilt angle on the lateral view of three-dimensional pelvic CT images of 40 patients (72 hips) with hip dysplasia. Forty normal hips from 40 patients were used as controls. The acetabular sector angle was measured as an index for acetabular coverage of the femoral head.
  
  
  RESULTS
  The mean acetabular tilt angle was increased in dysplastic hips compared with controls. In dysplastic hips, a posteriorly rotated acetabulum (increased acetabular tilt) was associated with increased acetabular anteversion and with decreased anterior and anterosuperior acetabular coverage. No correlation was found in controls. In dysplastic hips with a posterior acetabular deficiency, the acetabulum was rotated anteriorly (decreased acetabular tilt) compared with hips with anterior and lateral deficiencies.
  
  
  CONCLUSIONS
  We observed a correlation between the rotational position of the acetabulum in the pelvis with acetabular version and coverage in hip dysplasia. Our observations confirmed anterior rotation of the acetabular fragment during periacetabular osteotomies is an anatomically reasonable maneuver for hips with anterolateral acetabular deficiencies, while the maneuver can exacerbate posterior coverage and should be avoided in hips with a posterior acetabular deficiency.
  
  
  METHODS
  Level IV, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.
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: Masanori
authors.initials: M
authors.lastname: Fujii
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Taishi
authors.initials: T
authors.lastname: Sato
authors.forename: Mio
authors.initials: M
authors.lastname: Akiyama
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D005260:Female; D005270:Femur Head / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography; D055815:Young Adult