title: A retrospective comparative study of mortality and causes of death among patients with metal-on-metal and metal-on-polyethylene total hip prostheses in primary osteoarthritis after a long-term follow-up.
abstract: BACKGROUND
  All patients with total hip arthroplasty (THA), especially those with metal-on-metal (MM) THA, are exposed to metallic particles and ions, which may cause total or site-specific mortality. We analyzed the causes of total and site-specific mortality among a cohort of patients with MM and with metal-on-polyethylene (MP) THA after a long follow-up time.
  
  
  METHODS
  Standardized mortality ratios (SMR) of total and site-specific causes of death were calculated for 579 patients with MM (McKee-Farrar) and 1585 patients with MP (Brunswik, Lubinus) THA for primary osteoarthritis.
  
  
  RESULTS
  Mean follow-up time was 17.9 years for patients with MM and 16.7 years for patients with MP. Overall SMR was 0.95 for the MM cohort and 0.90 for the MP cohort, as compared to the normal population. Both cohorts showed significantly decreased mortality for the first decade postoperatively, equal mortality over the next 10 years, and significantly increased mortality after 20 years. Patients with MM THA had higher cancer mortality (SMR 1.01) than those with MP THA (SMR 0.66) during the first 20 years postoperatively, but not thereafter.
  
  
  CONCLUSIONS
  Both MM and MP prostheses are safe based on total and site-specific mortality of recipients during the first 20 postoperative years in comparison with the general population.
authors.affiliation: Research Institute of Military Medicine, Helsinki, Finland. tuomo.visuri@helsinki.fi
authors.forename: Tuomo
authors.initials: T
authors.lastname: Visuri
authors.forename: Håkan
authors.initials: H
authors.lastname: Borg
authors.forename: Pekka
authors.initials: P
authors.lastname: Pulkkinen
authors.forename: Pekka
authors.initials: P
authors.lastname: Paavolainen
authors.forename: Eero
authors.initials: E
authors.lastname: Pukkala
mesh_terms: D000328:Adult; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods / Q000401:mortality*; D002857:Chromium / Q000009:adverse effects / Q000737:chemistry / Q000627:therapeutic use; D003035:Cobalt / Q000009:adverse effects / Q000737:chemistry / Q000627:therapeutic use; D015331:Cohort Studies; D019544:Equipment Failure Analysis / Q000379:methods; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects* / Q000592:standards / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008670:Metals / Q000009:adverse effects* / Q000737:chemistry / Q000627:therapeutic use; D008875:Middle Aged; D009026:Mortality; D015207:Osteoarthritis, Hip / Q000601:surgery*; D020959:Polyethylene / Q000009:adverse effects* / Q000737:chemistry / Q000627:therapeutic use; D011183:Postoperative Complications / Q000401:mortality*; D011474:Prosthesis Design / Q000379:methods / Q000592:standards; D011475:Prosthesis Failure; D019919:Prosthesis Implantation / Q000379:methods / Q000401:mortality*; D012189:Retrospective Studies; D013995:Time
chemical_list: D008670:Metals; D002857:Chromium; D003035:Cobalt; D020959:Polyethylene