Federal health regulators have ordered DePuy Orthopaedics and 20 other hip implant makers to conduct studies of metal-on-metal hip implants to determine if they are shedding dangerous amounts of metallic debris in patients. In addition to DePuy, other device makers hit with the U.S. Food & Drug Administration’s (FDA) order include Zimmer, Stryker, Biomet and Wright Medical.

As we’ve reported in the past, metal-on-metal hip implants, including DePuy’s now-recalled ASR hip implant, have been the subject of growing safety concerns. The DePuy ASR hip implant was recalled last August, after data from a registry in the United Kingdom indicated a failure rate of 12 percent within five years of implantation. Since that recall, at least 1,000 DePuy ASR hip implant lawsuits have been filed by victims of the device in the U.S.

A second metal-on-metal device, the DePuy Pinnacle hip implant, has also been named in product liability lawsuits. Those actions claim that the design of the DePuy Pinnacle hip implant is substantially equivalent to the DePuy’s recalled ASR device. As we’ve reported previously, more than 1,300 people have filed an adverse event report with the FDA involving problems with a DePuy Pinnacle hip since the ASR hip implant recall was issued last year. However, the Pinnacle device remains on the market.

It is believed that many of the complications linked to the DePuy ASR implant and similar metal-on-metal devices are caused by wearing of their metal components, which can allow metal shavings to make their way into patients’ bloodstreams, leading to tissue breakdown, bone loss, and even the formation of non-cancerous tumors. This may cause cobalt poisoning, a disorder that, if left untreated, can put patients at risk of tinnitus (ringing in the ears), vertigo, deafness, blindness, optic nerve atrophy, convulsions, headaches, peripheral neuropathy, cardiomyopathy, and hypothyroidism.

According to a report published by The New York Times in March 2010, metal-on-metal hip implants have been used in about one-third of the approximately 250,000 hip replacements performed annually in this country. However, many of the nation’s leading orthopedic surgeons have reduced or stopped use of these devices because of concerns that they can cause severe tissue and bone damage.

Now the Times is reporting that the FDA contacted DePuy and the other 20 device makers via letter last Friday, directing them to determine if metal-on-metal hip implants are shedding high levels of metallic debris. They have also been told to determine how often their metal-on-metal hip implants fail prematurely. The agency is seeking information about the entire category of implants, not any single manufacturer’s device.

In a telephone interview with the Times, Dr. William H. Maisel, the deputy director for science at the FDA’s Center for Devices and Radiological Health, said that while the agency believes the devices do have benefits, there were significant enough medical concerns to warrant a broad review of metal-on-metal hips.

According to the Times, the FDA order allows manufacturers to determine how to conduct their studies, but they will be expected to collect patient data, including taking blood tests of implants recipients to determine if they have elevated levels of metal ions. The manufacturers have 30 days to file proposed plans with the FDA.