title: Less wear with aluminium-oxide heads than cobalt-chrome heads with ultra high molecular weight cemented polyethylene cups: a ten-year follow-up with radiostereometry.
abstract: OBJECTIVE
  Wear is a major contributor to osteolysis and aseptic loosening of total hip replacements (THR). Both alumina (Al(2)O(3)) and cobalt-chrome (CoCr) femoral heads are commonly used. We investigated wear comparing alumina heads to cobalt-chrome heads against conventional cemented polyethylene (PE) cups for up to ten years.
  
  
  METHODS
  Linear wear was measured with radiostereometry (RSA). Our material was derived from two prospective randomised trials that investigated fixation of femoral stems, not wear, and was evaluated retrospectively (Level III).
  
  
  RESULTS
  The mean (95% CI) proximal head penetration was 0.96 mm (0.68-1.23) in the cobalt-chrome group and 0.42 mm (0.30-0.53) in the alumina group at ten years (P = 0.001). The mean (95% CI) 3D penetration was 1.07 mm (0.79-1.35) and 0.53 mm (0.38-0.63), respectively, at ten years (P = 0.001).
  
  
  CONCLUSIONS
  Alumina heads performed better than cobalt-chrome heads in this study after ten-year follow-up.
authors.affiliation: Orthopaedic Department, Oslo University Hospital, N-0407, Oslo, Norway. jon.dahl@mac.com
authors.forename: Jon
authors.initials: J
authors.lastname: Dahl
authors.forename: Per
authors.initials: P
authors.lastname: Söderlund
authors.forename: Bo
authors.initials: B
authors.lastname: Nivbrant
authors.forename: Lars
authors.initials: L
authors.lastname: Nordsletten
authors.forename: Stephan M
authors.initials: SM
authors.lastname: Röhrl
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000537:Aluminum Oxide; D002484:Cementation; D002858:Chromium Alloys; D020099:Coated Materials, Biocompatible; D003035:Cobalt; D019544:Equipment Failure Analysis; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology; D020959:Polyethylene; D011446:Prospective Studies; D011474:Prosthesis Design; D011475:Prosthesis Failure / Q000209:etiology*
chemical_list: D002858:Chromium Alloys; D020099:Coated Materials, Biocompatible; D003035:Cobalt; D020959:Polyethylene; D000537:Aluminum Oxide