Hip replacements can do a lot of good, but they don't last forever.
To lower the failure rates of artificial hips, particularly in younger people, doctors have tried using metal-on-metal hip joints with larger heads.
But those metal-on-metal hips, which were supposed to be more durable, have their own problems.
Last year, the Food and Drug Administration told makers of the devices that they should monitor patients after surgery, after complaints about pain, infection and allergic reactions showed that some of the metal hips were failing much sooner than expected.
Two weeks ago, the British agency that oversees medical devices said that patients with metal-on-metal hips should get regular checkups.
And a new analysis published in the journal The Lancet confirms that metal-on-metal joints fail at higher rates than other types.
Stemmed metal-on-metal devices with larger heads fail at a higher rate than joints with smaller heads in both men and women, the study found. Women had more problem with the metal joints overall. They had a failure rate of 5 percent after five years compared to 3.7 percent of men. Those data apply to people aged 60. There were other chunks of data for other ages.
The numbers came from Britain's National Joint Registry, the world's largest source of data about people who have received hip replacements. Of the 402,051 who've had the surgery, 31,171 got stemmed metal-on-metal joints.
There's no similar registry in the U.S., which makes it hard for patients and doctors here to get solid information on the dozens of devices on the market. "We need a registry in the United States to show what's happening in our patient populations," says Joshua Jacobs, professor and chair of orthopedics at Rush University Medical Center in Chicago. A national registry is being developed, he says, but needs a way to get all hospitals to participate so the information's complete.
About one-third of hip replacements in the U.S. were metal-on-metal in 2009, the Lancet study says.
People with those hips shouldn't panic, Jacobs says. There are many different forms of metal-on-metal hips; not all have problems. And the vast majority of the people with the hips considered problematic are doing fine.
People with metal-on-metal hips should make sure to get regular routine checkups with their orthopedic surgeons, Jacobs says.
And any hip replacement recipient who experiences pain should get to the doctor promptly. The pain might be from something as harmless as bursitis, Jacobs says, but it still needs to be checked out.
"Just because their implant has a higher failure rate overall, doesn't mean that theirs will," he says.