Regulatory Focus™ > News Articles > New Safety Concerns About Metal-on-Metal Hip Implants Prompt MHRA Investigation

New Safety Concerns About Metal-on-Metal Hip Implants Prompt MHRA Investigation

Posted 31 January 2012 | By Alexander Gaffney, RAC 

The UK Medicines and Healthcare products Regulatory Agency (MHRA) is announcing that it is launching a safety investigation in light of concerns that patients fitted with metal-on-metal hip implants are at risk for a variety of adverse reactions.

An investigation by The Telegraph found that MHRA is "drawing up new advice for more than 30,000 Britons who have received 'metal-on-metal' devices because of fears that they are even more dangerous than previously thought."

Metal-on-metal implants are named for their metal bearing that rests in a metal hip socket. Earlier iterations of the device used a metal ball and a plastic hip socket. The use of the devices has been associated with metal shavings coming off of the devices and lodging themselves elsewhere in the patient's body.

The dangers associated with these metal filings include inflammation, muscle destruction, bone destruction and "systemic toxicity" from chromium and cobalt shavings in the body. A recent report from the British Hip Society said that 49% of all devices need to be replaced within 6 years of being implanted, while just 12-15% of similar non-metal-on-metal devices need to be replaced at the 5-year mark.

MHRA is seeking to reassure patients of the device's relative safety in the meantime.

 "On the evidence currently available the majority of patients implanted with metal-on-metal hip replacements are at low risk of developing any serious problems," said an MHRA spokesperson in a statement posted online.

"We are continuing to closely monitor all evidence. This needs more analysis before any conclusions can be drawn and further advice given. We have already taken prompt action to investigate safety concerns and have provided advice on patient management to relevant healthcare professionals."

While the concerns about the metal-on-metal hip implants aren't new - the devices were subject to recalls in 2010 from Johnson & Johnson subsidiary DePuy - the exceptionally high failure rates raised by the British Hip Society report and new toxicity concerns associated with the metal shavings have recast a harsh light on both the devices and European regulators.

Voluntary recalls initiated in the US by DePuy in August 2010 for their XL Acetabular system were reportedly done in response to data showing that the 5-year failure rate for the devices was roughly 13%. Device manufacturer Zimmer, Inc., issued a similar voluntary recall in July 2008 for their Durom Acetubular Component product. Zimmer cited a 1.5% estimated revision rate, but their "urgent device correction" letter does not specify the concerns that would later lead FDA to require postmarketing studies for the devices.

The timing of the renewed safety concerns is especially inopportune for EU medical device regulators, which are under renewed scrutiny as a result of scandal related to the purported failures of French breast implant manufacturer Poly Implant Prothese.

The issue could also raise flags in the US, where the US Food and Drug Administration (FDA) is preparing to enter Congressional negotiations regarding the reauthorization of the Medical Device User Fee Act(MDUFA). The negotiations come amidst some calls for tougher regulation for the agency's 510(k) medical device regulation pathway, which relies on devices being shown to be "substantially equivalent" to predicate devices already approved for marketing.

"The FDA is continuing to gather and review all available information about currently marketed metal-on-metal hip systems, including information related to adverse events that may be associated with increased levels of cobalt and chromium in the bloodstream," said FDA spokesperson Morgan Liscinsky in a statement to Regulatory Focus.

To that end, FDA issued orders in May 2011 for all metal-on-metal hip implant manufacturers to conduct postmarket surveillance studies on the devices, amounting to 145 orders sent to 21 manufacturers. The manufacturers will be "required to submit a research protocol to the FDA that addresses specific safety issues related to these devices," said Liscinsky.

"Data from the studies conducted will enable the agency to better understand these devices and their safety profiles."

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