“The FDA is correct in saying that there is no level above which we should be concerned and below which we shouldn’t have to worry,” Wright says. “Internal data at [Hospital for Special Surgery] show that some patients can have a high ion level and not have any problems, whereas others with a low level can have problems. So although it’s true that elevated blood levels of ions indicate that metal debris is showing up in the blood, that’s just one piece of the puzzle.”

In an effort to fit some of the puzzle pieces together, the FDA issued a safety communication in conjunction with the proposed rule change. It details the unique risks of all-metal implants and makes recommendations for monitoring the estimated 500,000 patients in the United States who have them.

The communication advises annual monitoring with a physical exam and routine X-rays for asymptomatic patients. More frequent follow-up is suggested for those at higher risk, such as women and patients who take corticosteroids or are overweight. Patients with adverse reactions, such as joint pain or swelling, should have imaging and blood ion tests every six months.

Dr. Noiseux, who closely follows patients with all-metal implants for at least five years, says the aim is to provide prompt and appropriate care to anyone with implant issues and to alert those who are currently asymptomatic to potential risks.

Wright agrees. He notes that studies show a significant number of asymptomatic patients – about 30 percent – have the beginnings of adverse tissue reactions. “So the message is, even if you’re feeling fine, the best thing to do is have a conversation with your clinician and come up with a plan for how often you should be followed. Complications such as tissue damage and implant loosening can be severe, and there should be a plan in place,” he says.

Alister Hart, MD, professor of orthopaedic surgery at the Royal National Orthopaedic Hospital in London, says the steps outlined in the FDA’s safety communication are similar to those that have been in place in the United Kingdom for several years.

“We find that clinical assessment is the most important factor, and blood metal ion tests and imaging are useful. However, none are definitive in isolation, and research is ongoing,” says, Dr. Hart, co-director of the London Implant Retrieval Centre, an independent research center that investigates why hip implants fail.

At one point, metal-on-metal implants accounted for approximately one-third of all hip replacement joints used in the United States, but experts say that number has plummeted to around 5 percent in recent years. “It’s clear there was a major mistake [with this device] and it would make absolutely no sense to put one in a patient now,” says Dr. Noiseux.

Wright points out that although the FDA’s move seems late in coming, the agency began asking manufacturers to start collecting data on patient outcomes as soon as reports of problems with the implants began to surface.

“Here was a device that looked concerning, but at first no one knew the scope of the problem,” says Wright, adding that the data-gathering process by the manufacturers took too long. “So this current ratcheting up – asking for safety and effectiveness data – is in response to that.”