Since January, the Food and Drug Administration (FDA) has received more than 5,000 reports about several all-metal hip replacement devices, which is more than the FDA received about those devices in the past four years combined, according to an analysis of federal data by The New York Times. The reports stack up even as researchers struggle to develop scientific studies of the health issues.
Barry Meier and Janet Roberts report:
The mounting complaints confirm what many experts have feared — that all-metal replacement hips are on a trajectory to become the biggest and most costly medical implant problem since Medtronic recalled a widely used heart device component in 2007. About 7,700 complaints have been filed in connection with that recall.
Hip replacement is one of the most common procedures in the U.S. Typically, replacements can last 15 years or more. In an all-metal hip replacement, the artificial ball and cup are both made of metal. The problems come just a few years after the replacement as the medical device wears. Tiny particles of cobalt and chromium metal grind off. Problems associated with the particles are not life-threatening, but can cause crippling tissue damage and severe pain.
Meier and Roberts write:
Most surgeons are abandoning the all-metal hips, saying they are unwilling to expose new patients to potential dangers when safer alternatives — mainly replacements that combine metal and plastic components — are available. Some researchers also fear that many all-metal hips suffer from a generic flaw. Current use of all metal devices has plummeted to about 5 percent of the market, though a few of the models are performing relatively well in select patients.
Studies are under development, but results may be years away. In May, the FDA ordered the device producers to study the frequency of failure and the consequences for patients. It is considered an unusual directive because, under FDA rules, many all-metal devices were sold without testing in patients or a requirement for producers to follow their performance, according to The New York Times report.
At this point, the producers face major challenges for developing protocols with which to study data and finding hundreds of patients willing to be part of those studies. Producers do not have their own patient registries, and researchers told Meier and Roberts that:
[I]t may be a year before standard protocols are formulated that may be central to the future studies, like a uniform procedure to measure metallic ions in a patient’s blood or how to calibrate diagnostic equipment to best detect tissue damage.
William Maisel, the chief scientist of the FDA division that oversees medical devices, told The New York Times that “he believed that producers would mount rigorous studies and find answers,” though “he acknowledged that it could take several years.”
Source: “Hip Implant Complaints Surge, Even as the Dangers Are Studied,” The New York Times, 8/22/11
Image by Cindy Funk, used under its Creative Commons license.
Rachel Petkewich is a freelance science writer and editor. She has worked as a research scientist in the chemical industry and spent eight years as a staff writer and editor at various science journals and magazines, including Chemical & Engineering News.