title: Risk of complication and revision total hip arthroplasty among Medicare patients with different bearing surfaces.
abstract: BACKGROUND
  To address the long-term problems of bearing surface wear and osteolysis associated with conventional metal-polyethylene (M-PE) total hip arthroplasty (THA), metal-metal (M-M), and ceramic-ceramic (C-C) bearings have been introduced. These bearing surfaces are associated with unique risks and benefits and higher costs. However the relative risks of these three bearings in an older population is unknown.
  
  
  OBJECTIVE
  We compared the short-term risk of complication and revision THA among Medicare patients having a primary THA with metal-polyethylene (M-PE), metal-metal (M-M), and ceramic-ceramic (C-C) bearings.
  
  
  METHODS
  We used the 2005 to 2007 100% Medicare inpatient claim files to perform a matched cohort analysis in three separate cohorts of THA patients (M-PE, M-M, and C-C) who were matched by age, gender, and US census region. Multivariate Cox proportional-hazards models were constructed to compare complication and revision THA risk among cohorts, adjusting for medical comorbidities, race, socioeconomic status, and hospital factors.
  
  
  RESULTS
  After adjusting for patient and hospital factors, M-M bearings were associated with a higher risk of periprosthetic joint infection (hazard ratio, 3.03; confidence interval, 1.02-9.09) when compared with C-C bearings (0.59% versus 0.32%, respectively). There were no other differences among bearing cohorts in the adjusted risk of revision THA or any other complication.
  
  
  CONCLUSIONS
  The risk of short-term complication (including dislocation) and revision THA were similar among appropriately matched Medicare THA patients regardless of bearing surface. Hard-on-hard THA bearings are of questionable value in Medicare patients, given the higher cost associated with their use and uncertain long-term benefits in older patients.
  
  
  METHODS
  Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143-0728, USA. kevin.bozic@ucsf.edu
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Bozic
authors.forename: Kevin
authors.initials: K
authors.lastname: Ong
authors.forename: Edmund
authors.initials: E
authors.lastname: Lau
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kurtz
authors.forename: Thomas P
authors.initials: TP
authors.lastname: Vail
authors.forename: Harry E
authors.initials: HE
authors.lastname: Rubash
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Berry
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D002516:Ceramics; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D006278:Medicare; D008670:Metals; D020959:Polyethylene; D011183:Postoperative Complications / Q000209:etiology* / Q000601:surgery; D016016:Proportional Hazards Models; D011474:Prosthesis Design; D012086:Reoperation; D018570:Risk Assessment; D012307:Risk Factors; D013499:Surface Properties; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
chemical_list: D008670:Metals; D020959:Polyethylene