title: Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal bearings.
abstract: Data from the national joint registries in Australia and England and Wales have revealed inferior medium-term survivorship for metal-on-metal (MoM) total hip arthroplasty (THA) than for metal-on-polyethylene (MoP) THA. Based on data from the Nordic Arthroplasty Register Association (NARA), we compared the revision risk of cementless stemmed THA with MoM and MoP bearings and we also compared MoM THA to each other.
  
  
  
  We identified 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM bearings (11,567 patients, 35%) or MoP bearings (21,111 patients, 65%). The patients were followed until revision, death, emigration, or the end of the study period (December 31, 2011), and median follow-up was 3.6 (interquartile range (IQR): 2.4-4.8) years for MoM bearings and 3.4 (IQR: 2.0-5.8) years for MoP bearings. Multivariable regression in the presence of competing risk of death was used to assess the relative risk (RR) of revision for any reason (with 95% confidence interval (CI)).
  
  
  
  The cumulative incidence of revision at 8 years of follow-up was 7.0% (CI: 6.0-8.1) for MoM bearings and 5.1% (CI: 4.7-5.6) for MoP bearings. At 6 years of follow-up, the RR of revision for any reason was 1.5 (CI: 1.3-1.7) for MoM bearings compared to MoP bearings. The RR of revision for any reason was higher for the ASR (adjusted RR = 6.4, CI: 5.0-8.1), the Conserve Plus (adjusted RR = 1.7, CI: 1.1-2.5) and "other" acetabular components (adjusted RR = 2.4, CI: 1.5-3.9) than for MoP THA at 6 years of follow-up.
  
  
  
  At medium-term follow-up, the survivorship for cementless stemmed MoM THA was inferior to that for MoP THA, and metal-related problems may cause higher revision rates for MoM bearings with longer follow-up.
authors.affiliation: Department of Orthopaedic Surgery, Section for Hip and Knee Replacement , Vejle Hospital , Vejle.
authors.forename: Claus
authors.initials: C
authors.lastname: Varnum
authors.forename: Alma B
authors.initials: AB
authors.lastname: Pedersen
authors.forename: Keijo
authors.initials: K
authors.lastname: Mäkelä
authors.forename: Antti
authors.initials: A
authors.lastname: Eskelinen
authors.forename: Leif Ivar
authors.initials: LI
authors.lastname: Havelin
authors.forename: Ove
authors.initials: O
authors.lastname: Furnes
authors.forename: Johan
authors.initials: J
authors.lastname: Kärrholm
authors.forename: Göran
authors.initials: G
authors.lastname: Garellick
authors.forename: Søren
authors.initials: S
authors.lastname: Overgaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008670:Metals; D008875:Middle Aged; D015999:Multivariate Analysis; D020959:Polyethylene; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections; D012042:Registries; D012086:Reoperation / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012307:Risk Factors; D012537:Scandinavian and Nordic Countries
chemical_list: D008670:Metals; D020959:Polyethylene