title: Mid-term survivorship and clinical outcomes of cobalt-chrome and oxidized zirconium on highly crosslinked polyethylene.
abstract: BACKGROUND
  The choice of bearing articulation for total hip arthroplasty in younger patients is amenable to debate. We compared mid-term patient-reported outcomes and survivorship across 2 different bearing articulations in a young patient cohort.
  
  
  METHODS
  We reviewed patients with cobalt-chrome or oxidized zirconium on highly crosslinked polyethylene who were followed prospectively between 2004 and 2012. Kaplan-Meier analysis was used to determine predicted cumulative survivorship at 5 years with all-cause and aseptic revisions as the outcome. We compared patient-reported outcomes, including the Harris hip score (HHS), Western Ontario and McMaster University Osteoarthritis Index (WOMAC) and Short-form 12 (SF-12) scores.
  
  
  RESULTS
  A total of 622 patients were followed during the study period. Mean follow-up was 8.2 (range 2.0-10.6) years for cobalt-chrome and 7.8 (range 2.1-10.7) years for oxidized zirconium. Mean age was 54.9 ± 10.6 years for cobalt-chrome and 54.8 ± 10.7 years for oxidized zirconium. Implant survivorship was 96.0% (95% confidence interval [CI] 94.9%-97.1%) for cobalt-chrome and 98.7% (95% CI 98.0%-99.4%) for oxidized zirconium on highly crosslinked polyethylene for all-cause revisions, and 97.2% (95% CI 96.2%-98.2%) for cobalt-chrome and 99.0% (95% CI 98.4%-99.6%) for oxidized zirconium for aseptic revisions. An age-, sex- and diagnosis-matched comparison of the HHS, WOMAC and SF-12 scores demonstrated no significant changes in clinical outcomes across the groups.
  
  
  CONCLUSIONS
  Both bearing surface couples demonstrated excellent mid-term survivorship and outcomes in young patient cohorts. Future analyses on wear and costs are warranted to elicit differences between the groups at long-term follow-up.
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Petis
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Vasarhelyi
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Brent A
authors.initials: BA
authors.lastname: Lanting
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: James L
authors.initials: JL
authors.lastname: Howard
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Douglas D R
authors.initials: DD
authors.lastname: Naudie
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Lyndsay E
authors.initials: LE
authors.lastname: Somerville
authors.affiliation: From the Division of Orthopedic Surgery, London Health Sciences Centre, University Hospital, London, Ont.
authors.forename: Richard W
authors.initials: RW
authors.lastname: McCalden
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000592:standards*; D002858:Chromium Alloys; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000592:standards*; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D063868:Patient Outcome Assessment; D020959:Polyethylene; D015040:Zirconium
chemical_list: D002858:Chromium Alloys; D020959:Polyethylene; D015040:Zirconium; C028541:zirconium oxide
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