title: Multilevel measurement of acetabular version using 3-D CT-generated models: implications for hip preservation surgery.
abstract: BACKGROUND
  Numerous structural deformities of the acetabulum are associated with hip osteoarthritis (OA). Acetabular retroversion has been implicated in the development of femoroacetabular impingement. However, it is unknown if retroversion occurs from isolated excessive bone in the superior acetabulum or a torsional phenomenon of the entire pelvic segment.
  
  
  OBJECTIVE
  A method was developed to measure acetabular version (AV) using 3-D models thus eliminating positional factors. This method was used to determine if acetabular retroversion is an isolated entity or an effect involving the entire pelvic segment containing the acetabulum.
  
  
  METHODS
  Fifty pelvic CT scans were selected from a large database. Measurements were performed for abduction, ischial spine position, and AV at multiple levels. The relationships between anteversion at multiple levels and between midacetabular anteversion and ischial spine position were analyzed.
  
  
  RESULTS
  The mean upper and midlevel acetabular anteversion values were 14.4° ± 10.5° and 21.3° ± 5.8°, respectively. The mean abduction was 39.7° ± 4.3°. The prevalence of acetabular retroversion was 7%. Females had greater anteversion than males at all levels. Correlations were found between Levels 1 and 4 version (r = 0.74) and the ischial spine index and Level 4 version (r = 0.67).
  
  
  CONCLUSIONS
  These data suggest retroversion involves the acetabulum at all levels and includes the entire pelvic segment containing the acetabulum and the ischial spine.
  
  
  CONCLUSIONS
  These data are relevant for surgeons in providing targets for normal positioning of the acetabulum during periacetabular osteotomies and acetabular recontouring procedures.
authors.affiliation: Dept of Orthopaedic Surgery, University of California Davis, 4860 Y Street, #3800, Sacramento, CA 95817, USA.
authors.forename: Aimee C
authors.initials: AC
authors.lastname: Perreira
authors.forename: John C
authors.initials: JC
authors.lastname: Hunter
authors.forename: Thaddeus
authors.initials: T
authors.lastname: Laird
authors.forename: Amir A
authors.initials: AA
authors.lastname: Jamali
mesh_terms: D000077:Acetabulum / Q000002:abnormalities / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D000293:Adolescent; D000328:Adult; D005260:Female; D006617:Hip Dislocation / Q000453:epidemiology / Q000473:pathology*; D006621:Hip Joint / Q000601:surgery*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D010384:Pelvic Bones / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods*; D055815:Young Adult