title: Five-year comparison of oxidized zirconium and cobalt-chromium femoral components in total knee arthroplasty: a randomized controlled trial.
abstract: BACKGROUND
  In vitro analysis has shown that oxidized zirconium on ultra-high molecular weight polyethylene has better wear properties than cobalt-chromium on ultra-high molecular weight polyethylene. The purpose of this study was to determine if oxidized zirconium femoral components performed better than cobalt-chromium in vivo and if the use of oxidized zirconium components had clinical adverse effects.
  
  
  METHODS
  Forty consecutive patients (eighty knees) underwent simultaneous bilateral cruciate-retaining total knee arthroplasty for primary osteoarthritis from January 2002 to December 2003. For each patient, the knees were randomized to receive the oxidized zirconium femoral component, with the contralateral knee receiving the cobalt-chromium component. Outcome measures included the Western Ontario and McMaster Universities Osteoarthritis Index, Knee Injury and Osteoarthritis Outcome Score, Knee Society score, and British Orthopaedic Association patient satisfaction scale. Radiographic outcomes include the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system and measurement of radiographic wear. Patients and assessors were blinded to the treatment groups and results.
  
  
  RESULTS
  There were no significant differences in clinical, subjective, and radiographic outcomes between the two implants at five days, six weeks, and one, two, or five years postoperatively. At five years following surgery, 38% of the patients preferred the cobalt-chromium knee compared with 18% who preferred the oxidized zirconium knee (p = 0.02) and 44% had no preference.
  
  
  CONCLUSIONS
  Five-year outcomes after total knee arthroplasty with oxidized zirconium and cobalt-chromium femoral components showed no significant differences in clinical, subjective, and radiographic outcomes. Patients had no preference or preferred the cobalt-chromium prosthesis to the oxidized zirconium prosthesis at the time of the five-year follow-up. There were no adverse effects associated with the use of oxidized zirconium femoral implants.
authors.affiliation: North Sydney Orthopaedic and Sports Medicine Centre, Wollstonecraft, New South Wales, Australia.
authors.forename: Catherine
authors.initials: C
authors.lastname: Hui
authors.forename: Lucy
authors.initials: L
authors.lastname: Salmon
authors.forename: Shinichi
authors.initials: S
authors.lastname: Maeno
authors.forename: Justin
authors.initials: J
authors.lastname: Roe
authors.forename: William
authors.initials: W
authors.lastname: Walsh
authors.forename: Leo
authors.initials: L
authors.lastname: Pinczewski
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D002858:Chromium Alloys / Q000494:pharmacology*; D016001:Confidence Intervals; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D010149:Postoperative Pain / Q000503:physiopathology; D018579:Patient Selection; D011183:Postoperative Complications / Q000503:physiopathology; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D020127:Recovery of Function; D018570:Risk Assessment; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D015040:Zirconium / Q000494:pharmacology*
chemical_list: D002858:Chromium Alloys; D015040:Zirconium