title: Revision rates for metal-on-metal hip resurfacing and metal-on-metal total hip arthroplasty - a systematic review.
abstract: OBJECTIVE
  To compare revision rates of metal-on-metal (MoM) hip resurfacing (HRS) and MoM total hip arthroplasty (THA), as well as the primary causes for revisions.
  
  
  METHODS
  The PubMed database was queried for potentially relevant articles addressing MoMTHA and MoMHRS, a total of 51 articles were included.
  
  
  RESULTS
  The review includes a total number of 5,399 MoMHRS and 3,244 THA prosthesis and the reasons for prosthesis failure were divided into 7 categories and the main causes discussed. The overall MoMTHA revision rate was 4.7% after 6.9 years. MoMHRS revision rate was 5.9% after 5.7 years. The odds ratio was 1.25 (1.03:1.53) 95% CI (p = 0.03) (MoMHRS vs. MoMTHA).The studies of hip prostheses were separated into 2 categories of short- and long-term (more or less than 5 years). Short-term revision rate for MoMTHA was 4.5% after 4.8 years, and for MoMHRS 4.0% after 4.2 years. The odds ratio was 1.09 (0.82:1.43) 95% CI (0 = 0.56) (MoMTHA vs. MoMHRS). Long-term revision rate for MoMTHA was 5.2% after 7.7 years and 8.2% after 7.6 years for MoMHRS. The odds ratio was 1.58 (1.53:1.96) 95% CI (p = 0.0001) (MoMHRS vs. MoMTHA).Revision causes were divided into 7 main categories. The most common cause for revision for both MoMTHA and MoMHRS was loosening 47.6% vs. 37.7%, fracture (MoMTHA 7.69%; MoMHRS 19.62%), metal reactions (MoMTHA 7.69%; MoMHRS 26.92%) infection (MoMTHA 12.08%; MoMHRS 6.54%), instability (MoMTHA 9.13%; MoMHRS 2.69%), manufacturer defect 6.73% for MoMTHA and nonreported for MoMHRS, and miscellaneous (MoMTHA 7.69%; MoMHRS 6.54%) was stated.
  
  
  CONCLUSIONS
  The comparison of MoMHRS and MoMTHA revision rates showed no difference in the short term, however in the longer term, the revision rate of MoMHRS was significantly higher than for MoMTHA. The linear increase in revision rate of MoMHRS may indicate a progression in failure.
authors: Department of Orthopaedic Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen - Denmark.
authors: Sofie-Amalie L
authors: SL
authors: Ras Sørensen
authors: Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen, Copenhagen - Denmark.
authors: Henrik L
authors: HL
authors: Jørgensen
authors: Department of Orthopaedic Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen - Denmark.
authors: Sune L
authors: SL
authors: Sporing
authors: Department of Orthopaedic Surgery, Bispebjerg Hospital, University of Copenhagen, Copenhagen - Denmark.
authors: Jes B
authors: JB
authors: Lauritzen
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation* / Q000706:statistics & numerical data; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D011474:Prosthesis Design / Q000009:adverse effects; D011475:Prosthesis Failure / Q000009:adverse effects; D012086:Reoperation / Q000706:statistics & numerical data; D013997:Time Factors