Saturday, November 5, 2011

California Technology Assessment Forum (CTAF) Requested to Reveiw Evidence for MoM resurfacing systems

CTAF was requested to review evidence for metal on metal hip resurfacing as an alternative to total hip replacement. Below are excerpts from that report

  • In the 50's, the concept of resurfacing the arthritic socket as well as the femoral head emerged but the materials used (first Teflon and then acrylic cement) and the design flaws led to numerous device failures and adverse events.
  •  The third generation of hip resurfacing emerged in the 90's in England and while there are 10 different commercially available hip resurfacing systems [one of them by depuy- but not approved in the US for sale] only three are approved by the FDA:
    • Cormet
    • Conserve plus
    • Birmingham
  • All three use a metal on metal Chromium-cobalt articulation
  • The potential advantages of resurfacing over total hip replacement is that it preserves the femoral head and only replaces the joint. Thus it can be a less complex surgery.
  • In 2007, CTAF concluded that all peer reviewed literature had not kept pace with the changes in hip resurfacing technology.  That is, there were no randomized controls.
  • The 2010 assessment was conducted to review the peer-reviewed literature on the 3 FDA approved MoM approved systems.
  • In August 2010, Depuy issued a voluntary recall of their ASR hip resurfacing system as they were undergoing clinical trials in the US.
  • There were 5 criteria judged by the committee to be required to provide assurances of safety of these systems:
    • technology must have final approval from the appropriate govt regulatory bodies. 
      • All 3  systems passed the FDA that were being actively being marketed.
    • Scientific evidence must permit conclusions concerning the effectiveness of the technology regarding health outcomes.
      • All three systems passed this criterion
    • Technology must improve health outcomes
      • Most of the studies and tests conducted found no difference in patient outcome and substantially more revisions.
      • Although resurfacing has some benefits for younger patients, the risks are higher revision rates and elevated MoM levels are of concern.
      • Test Criteria 3 was not met
    • Technology must be as beneficial as any established alternatives
      • Because the 3rd criteria was not met, the 4th criteria cannot be met since the primary alternative is total hip replacement and there have been no significant studies to demonstrate this procedure works as well.
    • The improvement must be attainable outside of the investigational setting.
      • Since criterion 3 and 4 were not met, the 5th criteria can't be met.
So the big conclusion is that "It is not possible to conclude from the current peer reviewed literature that the currently approved hip resurfacing systems in the US improve health outcomes comparably with the current standard of care, total hip replacement.  Further, the report concluded that the current metal on metal on metal resurfacing systems on the market which have been approved by the FDA do not meet 3 of the 5 criteria for safety and improvement in health outcomes for patients as an alternative to hip replacement therapy.

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