A metal-on-metal hip joint that was removed from a patient.

After an estimated 500,000 patients in the U.S. have received a type of artificial hip that is failing early in many cases, the Food and Drug Administration is proposing rules that could stop manufacturers from selling such implants.

Under the proposal, makers of artificial hips with all-metal components would have to prove the devices were safe and effective before they could continue selling existing ones or obtain approval for new all-metal designs.

Currently, companies have to show only that their devices resemble ones already on the market, and they are not required to conduct clinical studies before selling them.

The FDA action is intended to close a loophole in the 1976 federal law under which medical devices were first regulated. It is the agency’s first use of powers that Congress granted to it last year to deal with medical devices, like all-metal hips, that have been in regulatory limbo for decades.

The move comes amid one of the biggest device-related failures in decades. Just a few years ago, all-metal hips – implants in which the ball and cup component is made from a metallic alloy – were used in 1 of every 3 joint replacement procedures performed annually in the U.S.

Traditional hip replacements, which are made of materials like plastic and metal, typically last 15 years before wearing out. But the all-metal hips, which companies rarely tested in patients before aggressively marketing them, are failing at high rates not long after implantation.

As a result, thousands of patients have been forced to undergo painful and costly operations to replace the devices. In addition, tiny particles of metallic debris released as the artificial joints move have caused severe tissue and bone damage in hundreds of patients, leaving some of them disabled.

Dr. William H. Maisel, deputy director for science at the FDA, said the agency’s proposal would require makers of all-metal hips to produce clinical data to justify their use because of the “large number of patients who received these products and the numbers of adverse events associated with them.”

The use of all-metal implants has plummeted, with the devices now accounting for about 5 percent of hip implants. For some of those devices, which are used in a procedure called resurfacing that is an alternative to total hip replacement, the FDA already requires clinical trials before granting approval.

The impact of the proposal on manufacturers of traditional all-metal hips will not be immediate, and industry lobbyists may oppose its adoption or seek to modify it. Agency officials said it would most likely take a year for the rules to be finalized; after that, producers will have 90 days to submit clinical data to support a device’s safety and effectiveness.

In 2011, the FDA ordered manufacturers of all-metal hips to conduct post-marketing studies to determine, among other things, whether the implants were shedding high levels of metallic debris. Maisel said he expected that device makers might try to use data from those studies to satisfy the proposed requirements.

If a company decided not to submit clinical data or if the information failed to meet agency standards, it would have to stop selling the implant.

The regulatory limbo involving all-metal hips resulted from the Medical Device Amendments of 1976.

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