title: Alternative bearings in total knee arthroplasty: risk of early revision compared to traditional bearings: an analysis of 62,177 primary cases.
abstract: OBJECTIVE
  There is no substantial clinical evidence for the superiority of alternative bearings in total knee arthroplasty (TKA). We compared the short-term revision risk in alternative surface bearing knees (oxidized zirconium (OZ) femoral implants or highly crosslinked polyethylene (HXLPE) inserts) with that for traditional bearings (cobalt-chromium (CoCR) on conventional polyethelene (CPE)). The risk of revision with commercially available HXLPE inserts was also evaluated.
  
  
  METHODS
  All 62,177 primary TKA cases registered in a Total Joint Replacement Registry between April 2001 and December 2010 were retrospectively analyzed. The endpoints for the analysis were all-cause revisions, septic revisions, or aseptic revisions. Bearing surfaces were categorized as OZ-CPE, CoCr-HXLPE, or CoCr-CPE. HXLPE inserts were stratified according to brand name. Confounding was addressed using propensity score weights. Marginal Cox-regression models adjusting for surgeon clustering were used.
  
  
  RESULTS
  The proportion of females was 62%. Average age was 68 (SD 9.3) years, and median follow-up time was 2.8 (IQR 1.2-4.9) years. After adjustments, the risks of all-cause, aseptic, and septic revision with CoCr-HXLPE and OZ-CPE bearings were not statistically significantly higher than with traditional CoCr-CPE bearings. No specific brand of HXLPE insert was associated with a higher risk of all-cause, aseptic, or septic revision compared to CoCr-CPE.
  
  
  CONCLUSIONS
  At least in the short term, none of the alternative knee bearings evaluated (CoCr-HXLPE or OZ-CPE) had a greater risk of all-cause, aseptic, and septic revision than traditional CoCr-CPE bearings.
authors.affiliation: Department of Surgical Outcomes and Analysis, Kaiser Permanente, San Diego, CA, USA. maria.cs.inacio@kp.org
authors.forename: Maria C S
authors.initials: MC
authors.lastname: Inacio
authors.forename: Guy
authors.initials: G
authors.lastname: Cafri
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Paxton
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kurtz
authors.forename: Robert S
authors.initials: RS
authors.lastname: Namba
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D002858:Chromium Alloys / Q000009:adverse effects; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D020959:Polyethylene / Q000009:adverse effects; D011474:Prosthesis Design / Q000009:adverse effects*; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D015040:Zirconium / Q000009:adverse effects
chemical_list: D002858:Chromium Alloys; D020959:Polyethylene; D015040:Zirconium