MATTHEW PERRONEWASHINGTON (AP) â¿¿ Government health experts said Thursday there are few reasons to continue using metal-on-metal hip implants, amid growing evidence that the devices can break down early and expose patients to dangerous metallic particles. The Food and Drug Administration asked its 18-member panel to recommend guidelines for monitoring more than a half-million U.S. patients with metal hip replacements. The devices were originally marketed as a longer-lasting alternative to older ceramic and plastic models. But recent data from the U.K. and other foreign countries suggests they are more likely to deteriorate, exposing patients to higher levels of cobalt, chromium and other metals. While the FDA has not raised the possibility of removing the devices from the market, most panelists said there were few, if any, cases where they would recommend implanting the devices. "I do not use metal-on-metal hips, and I can see no reason to do so," said Dr. William Rohr of Mendocino Coast District Hospital, who chaired the meeting. For decades nearly all orthopedic implants were coated with plastic or ceramic. But in the last 10 years some surgeons began to favor all-metal implants, after laboratory tests suggested the devices would be more resistant to wear and reduce the chances of dislocation. But recent data gathered from foreign registries shows the devices fail at a higher rate than older implants. That information comes on top of nearly 17,000 reports to the FDA of problems with the implants, which sometimes require invasive surgery to replace them. The pain and inflammation reported by patients is usually caused by tiny metal particles that seep into the joint, damaging the surrounding tissue and bone. The long-term effects of elevated metal levels in the bloodstream are not clear, though some studies have suggested links to neurological and heart problems. About 400,000 Americans get a hip replacement each year to relieve pain and restore motion affected by arthritis or injury. Metal hips accounted for about 27 percent of all hip implants in 2010, down from nearly 40 percent in 2008. Doctors have begun turning away from the implants amid several high-profile recalls, including J&J's recall of 93,000 metal hips in 2010.