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FDA Seeks Advice on Metal-on-Metal Hip Replacements
There are two categories of these systems:
1. Metal-on-metal total hip replacement systems consisting of a metal ball (femoral head), a metal femoral stem in the thighbone, and a metal cup in the hip bone (acetabular component).
2. Metal-on-metal hip resurfacing systems consisting of a trimmed femoral head capped with a metal covering and a metal cup in the hip bone (acetabular component).
Hip replacement surgery is intended to provide increased patient mobility and reduce pain by replacing the damaged hip joint in patients where there is evidence of sufficient sound bone to seat and support the components.
In May 2011, the agency issued an order for manufacturers of MoM hip systems to conduct post-market surveillance studies to collect more safety data on these devices, including data related to metal ion concentrations in the bloodstream.
The agency is currently considering whether to make MoM hip systems subject to more rigorous testing and premarket review requirements.
A recent study noting an increased failure rate related to those systems that utilize large-diameter femoral heads has added to the agency’s existing concerns over the safety of MoM hip systems.
“We are asking outside scientific and medical experts to discuss recent information on these devices so that the agency can continue to make reliable safety recommendations to patients and their health care providers,” said William Maisel, M.D., M.P.H., deputy director of science at FDA’s Center for Devices and Radiological Health (CDRH).
Experts on CDRH’s Orthopedic Devices Panel will discuss:
- Failure rates and modes
- Metal ion testing
- Imaging methods
- Local and systemic complications
- Patient risk factors;and
- Considerations for follow-up after surgery