title: A 5-year survival analysis of 160 Biomet Magnum M2 metal-on-metal total hip prostheses.
abstract: BACKGROUND
  Large-head metal-on-metal (MoM) total hip arthroplasties (THA) are associated with high failure rates and possible pseudotumour formation. This study reports the first results of 160 Biomet Magnum M2 large-head MoM total hip articulations.
  
  
  METHODS
  From 2006 to 2010 the Reinier de Graaf Hospital implanted 160 large-head Magnum M2 MoM THAs (Biomet Inc. Warsaw, Indiana, USA) in 150 patients. These patients were recalled after a warning from the Dutch Orthopaedic Association. Patients were offered a clinical and radiographic assessment of the hip prosthesis, serum control on cobalt and chromium ions, and an ultrasound of the hip. If indicated, additional MARS-MRI or CT scan was performed. Descriptive statistical analysis, correlations, t-tests, non-parametric tests and implant survival were calculated.
  
  
  RESULTS
  The mean follow-up was 6.1 years (4.8-8.4). A cumulative survival rate of 93.1% (95% CI: 88.3-98%) was found after 5 years. Reasons for revision were loosening, pain, infection and pseudotumour formation. The prevalence of pseudotumour formation around the prostheses was 8.75%.
  
  
  CONCLUSIONS
  This study reports the first results of 160 MoM THAs implanted in our clinic from 2006-2010. In total, 13 (8.1%) of the THAs were eligible for revision after the recall. In most patients the reason for revision was pseudotumour formation. A total of 14 (8.75%) pseudotumours were diagnosed at the first recall. These results show that a comprehensive follow-up strategy is essential for MoM THAs to promptly identify and manage early complications.
authors.affiliation: Department of Orthopaedics, Reinier de Graaf Hospital, Delft - The Netherlands.
authors.forename: Maarten C
authors.initials: MC
authors.lastname: Koper
authors.affiliation: Department of Orthopaedics, Reinier de Graaf Hospital, Delft - The Netherlands.
authors.forename: Nina M C
authors.initials: NM
authors.lastname: Mathijssen
authors.affiliation: Department of Orthopaedics, Reinier de Graaf Hospital, Delft - The Netherlands.
authors.forename: Stephan B W
authors.initials: SB
authors.lastname: Vehmeijer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002857:Chromium / Q000097:blood; D003035:Cobalt / Q000097:blood; D019544:Equipment Failure Analysis / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006104:Granuloma, Plasma Cell / Q000000981:diagnostic imaging / Q000453:epidemiology; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000097:blood / Q000401:mortality / Q000601:surgery*; D011475:Prosthesis Failure; D012086:Reoperation; D016019:Survival Analysis; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D002857:Chromium; D003035:Cobalt