title: Five-year results of two cemented hip stem models each made of two different alloys.
abstract: BACKGROUND
  The aim of this study was to compare the influence of two different cemented hip stems each made of two different alloys concerning survival and outcome.
  
  
  METHODS
  The 5-year results with 161 Mueller straight stems made of cobalt chromium (SS CoCr), 272 Mueller straight stems made of titanium (SS Ti), 233 Mueller SL stems made of titanium (SL Ti) and 255 SL stems made of cobalt chromium (SL CoCr) implanted consecutively in this order were compared. All patients were followed up prospectively during the first 5 years after implantation. The evaluation of the results was retrospective.
  
  
  RESULTS
  The survival rates for aseptic loosening were 100% (SS CoCr), 92.8% (SS Ti), 81.6% (SL Ti) and 97.8% (SL CoCr). Clinical and radiological outcomes like pain occurrence, use of pain medication, ability to climb stairs, amount of stem subsidence and osteolysis correlated statistically significantly with the results of the survival rates. Concerning the two alloys, chromium cobalt showed better results, and concerning the two designs, the straight stem had a better outcome. For the four prostheses being compared, the results were influenced more by the alloy than by the design, and the small-sized titanium stems were more susceptible to undergoing revision than the large-sized prostheses.
  
  
  CONCLUSIONS
  Stem design and even more alloy may influence the survival rate and clinical outcome. Evaluating the results, we recommend the use of the classic straight stem prosthesis made of cobalt chromium.
authors.affiliation: Orthopaedic Department, Kantonsspital Liestal, Rheinstrasse 26, 4410, Liestal, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Schweizer
authors.forename: M
authors.initials: M
authors.lastname: Lüem
authors.forename: U
authors.initials: U
authors.lastname: Riede
authors.forename: P
authors.initials: P
authors.lastname: Lindenlaub
authors.forename: P E
authors.initials: PE
authors.lastname: Ochsner
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D001672:Biocompatible Materials / Q000627:therapeutic use; D001843:Bone Cements / Q000627:therapeutic use; D002858:Chromium Alloys / Q000627:therapeutic use; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D014025:Titanium / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D001672:Biocompatible Materials; D001843:Bone Cements; D002858:Chromium Alloys; D014025:Titanium