title: Comparison of ten-year survivorship of hip prostheses with use of conventional polyethylene, metal-on-metal, or ceramic-on-ceramic bearings.
abstract: BACKGROUND
  To improve the long-term performance of hip prostheses, alternative bearings with metal-on-metal (MoM) and ceramic-on-ceramic (CoC) couples have been introduced. Although currently the results from the use of these bearings are in the midterm stage, there have been few comparative studies of these different bearings.
  
  
  METHODS
  From 2000 to 2002, 487 total hip replacements were performed with use of a BICON-PLUS acetabular cup and an SL-PLUS femoral stem (Plus Orthopedics, Rotkreuz, Switzerland, now Smith & Nephew Orthopaedics). The patients were divided into three groups according to the type of bearing that was used: an MoM group (sixty-nine prostheses), a metal-on-polyethylene (MoP) group (200 prostheses), and a CoC group (218 prostheses). Patient demographic data and data with regard to revision operations were evaluated from the hospital computer database. The mean follow-up period was 8.5 years (range, 6.9 to 10.5 years). Patient activity was assessed with use of the University of California at Los Angeles activity scale.
  
  
  RESULTS
  The mean patient age was sixty years at the time of the index arthroplasty in the MoM and CoC groups, and seventy-one years in the MoP group. Based on a scale of ten, the mean postoperative activity level was six in the CoC group, five in the MoM group, and four in the MoP group. Survival at ten years with regard to revision for any reason was 0.984, 0.956, and 0.879 for the MoP, CoC, and MoM groups, respectively. When revision for any reason was considered as the end point, survival of the MoM bearings was significantly worse than that of the MoP bearings (p = 0.005). Survival at ten years with regard to revision for aseptic loosening was 0.995, 0.990, and 0.894 for the MoP, CoC, and MoM groups, respectively. When revision for aseptic loosening was considered as the end point, survival of the MoM group was significantly worse than that of either the MoP group (p = 0.001) or the CoC group (p = 0.003).
  
  
  CONCLUSIONS
  When comparing two groups of patients of similar mean age and mean activity level undergoing total hip arthroplasty with the use of alternative bearings, CoC bearings had better survival than did MoM bearings at the ten-year follow-up; the difference was significant when revision for aseptic loosening was defined as a failure. However, neither the CoC nor the MoM alternative bearings provided improved midterm results when compared with the results of the conventional MoP bearings. For older, less active patients, traditional metal-on-polyethylene bearings are the appropriate choice.
  
  
  METHODS
  Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Valdoltra Orthopaedic Hospital, Jadranska c. 31, SI-6280 Ankaran, Slovenia. ingrid.milosev@ijs.si
authors.forename: Ingrid
authors.initials: I
authors.lastname: Milošev
authors.forename: Simon
authors.initials: S
authors.lastname: Kovač
authors.forename: Rihard
authors.initials: R
authors.lastname: Trebše
authors.forename: Vesna
authors.initials: V
authors.lastname: Levašič
authors.forename: Venčeslav
authors.initials: V
authors.lastname: Pišot
mesh_terms: D000367:Age Factors; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D002516:Ceramics; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011474:Prosthesis Design / Q000379:methods*; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000503:physiopathology / Q000601:surgery; D012086:Reoperation / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D013314:Stress, Mechanical; D013997:Time Factors; D014025:Titanium; D016896:Treatment Outcome; D016474:Weight-Bearing / Q000502:physiology
chemical_list: D020959:Polyethylene; D014025:Titanium