British Experts Want Doctors to Stop Using Metal-on-Metal Hips LONDON (AP) - British experts at the world's biggest artificial joint registry said doctors should stop using metal-on-metal hip replacements, citing an analysis showing they have to be fixed or replaced more often than other implants. All-metal hip joints were already under scrutiny over how long they last. Last year, regulators in the United States asked makers to conduct safety studies on them. Most artificial hip joints are plastic or ceramic. In the new study, experts analyzed data for more than 400,000 hip replacements from the National Joint Registry of England and Wales from 2003 to 2011. More than 31,000 of those were metal-on-metal devices. After five years, about 6 percent of people with the metal-on-metal variety needed surgery to fix or replace them. That compares with 1.7 to 2.3 percent of people who had ceramic or plastic joints. Doctors usually expect hip joints to last at least a decade. The study was published online Tuesday in The Lancet, a British medical journal. It was financed by the National Joint Registry.