title: Acetabular cup positioning in revision total hip arthroplasty with Paprosky type III acetabular defects: Martell radiographic analysis.
abstract: OBJECTIVE
  This study evaluates acetabular cup position in the setting of revision total hip arthroplasty (THA) with severe acetabular bone defects.
  
  
  METHODS
  With a definition of safe zone of abduction (30-50°) and anteversion (5-25°), acetabular cup position was measured by a digital image analysis program for 34 patients with Paprosky type III acetabular bone defects.
  
  
  RESULTS
  There were 24 cups (71%) for abduction and 26 cups (76%) for anteversion located in the safe zone. Nineteen cups (56%) were within the safe zone for both abduction and anteversion. There was no dislocation, however one cup out of the safe zone resulted in early cup failure due to aseptic loosening.
  
  
  CONCLUSIONS
  The acetabular cup positioning in patients with Paprosky type III defects was 'optimal' in half of the cases. The prevalence of optimal acetabular cup position was similar to those reported in primary THA, suggesting that the presence of a large acetabular bone defect may not be a significant risk factor for suboptimal acetabular cup positioning in the setting of revision THA.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, MA, USA.
authors.forename: Ho-Rim
authors.initials: HR
authors.lastname: Choi
authors.forename: David
authors.initials: D
authors.lastname: Anderson
authors.forename: Scott
authors.initials: S
authors.lastname: Foster
authors.forename: Matthew
authors.initials: M
authors.lastname: Beal
authors.forename: Jo Ann
authors.initials: JA
authors.lastname: Lee
authors.forename: Christopher
authors.initials: C
authors.lastname: Barr
authors.forename: Henrik
authors.initials: H
authors.lastname: Malchau
authors.forename: Joseph
authors.initials: J
authors.lastname: McCarthy
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kwon
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging* / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D019544:Equipment Failure Analysis; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011475:Prosthesis Failure / Q000209:etiology; D011859:Radiography; D011871:Radiology / Q000379:methods; D012086:Reoperation; D012189:Retrospective Studies