Friday, June 29, 2012

FDA Panel Discussing Safety of Metal-On-Metal Hip Implants

By Jennifer Corbett Dooren

Wall Street Journal
WASHINGTON--The Food and Drug Administration on Wednesday convened a two-day advisory panel meeting to discuss the safety of metal hip implants, amid concerns there are more side effects than with implants made out of such materials as ceramic or plastic.

The advisory panel is being asked to make recommendations whether additional warnings and other information is needed for metal hip systems, and to make recommendations about which types of patients would benefit the most from metal implants as well those who shouldn't get them. The panel is not being asked to discuss regulatory changes like requiring the devices to go through more stringent clinical testing.

In 2010, Johnson & Johnson's (JNJ) DePuy Orthopaedics Inc. recalled 93,000 of its ASR total hip implants after they were linked to higher failure rates than other implants. The ASR device is no longer sold but is still implanted in many patients, and the company faces about 6,000 lawsuits.

One of the safety concerns involves the wear on the implants and its breaking down of the metal, which in some patients causes joint and muscle destruction and other health problems.

Elizabeth Frank, an FDA medical reviewer, said Tuesday that patients vary in their reactions to metal particulate, with some having a severe inflammatory response to having no reaction.

Because hip implants were on the market before FDA started regulating medical devices in 1976, such companies as DePuy and Wright Medical Group Inc. (WMGI) only need to show a hip implant is similar to a device already on the market and don't need to conduct clinical studies showing safety and effectiveness, a process that has been criticized by some policy makers and many patients.

Major changes to devices, however, do require additional testing, and hip resurfacing systems, including ones made by Smith & Nephew PLC (SNN), are required to go through FDA's premarket approval process, which requires companies to conduct clinical studies in humans looking at the devices' performance. The FDA said other companies with metal hip implants on the market include Biomet Inc., Zimmer Holdings Inc. (ZMH) and Encore Medical L.P.

There are about 400,000 hip implant surgeries in the U.S. each year. About 25% of surgeries involve metal-on-metal implants, according to recent U.S. government data.

Information from patient registries outside of the U.S. suggest more patients need to have the metal implants fixed than other types of implants. The U.S. doesn't have a national registry and studies looking at implant failure rates in the U.S. have been mixed. Some data suggest women have higher failure, or revision rates, compared to men while other data suggests there might be more problems with implants that have a larger component, called the femoral head, than smaller components.

"Could it be the size of the head when we are attributing all the problems to metal?" said Raj Rao, a panel member from the orthopaedic surgery department of the Medical College of Wisconsin.

Although the panel had not formally started addressing FDA's questions Wednesday, preliminary discussion suggests the panel may struggle to adopt clear recommendations given the number of products and conflicting data.

"I don't believe the failure mechanism of these devices is the same," said Edward Cheng, a panelist from the University of Minnesota Medical School and Cancer Center.

Information prepared for the meeting by the FDA showed there's been almost 17,000 adverse-event reports submitted to FDA involving the metal-on-metal implants from 1992 through 2011. There were 22,000 for nonmetal hip implants. Of the metal-on-metal reports, about 12,000 were submitted in 2011 with 9,000 attributed to the DePuy ASR. The reports cited problems including the need for revision--or additional surgery to fix or replace the implant--pain, dislocation and bone infections.

In a presentation to the panel, Paul Voorhorst, the director for biostatistics and data management for DePuy Orthopaedics, said not all "metal-on-metal implants are the same and each should be evaluated on its own merits." Mr. Voorhorst didn't specifically mention the recalled ASR product and instead focused on another product. However, he said the company believes all patients with joint replacements need to be monitored

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