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FDA panel sees little use for metal-on-metal hips
By Matthew Perrone on June 28,
2012 (FiDA blog bold)
WASHINGTON (AP) — 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.
FDA's experts said Thursday that
patients complaining of pain and other symptoms should get regular X-rays and
blood testing for metal levels. However, panelists pointed out the problems
with the accuracy of blood tests and the difficulties of interpreting the
results. There are no standard diagnostic kits for sale that test for chromium
and other metals
For patients who are not
experiencing pain, panelists said annual X-rays would be sufficient to monitor
their implants.
If the FDA ultimately follows the
group's advice, U.S. recommendations would be less involved than those already
in place overseas.
Earlier this year U.K. regulators
recommend that all people who have the implants get yearly blood tests to make
sure no dangerous metals are seeping into their bodies.
FDA regulators have suggested they
want to take more time to sort out the differences between various implants and
patient groups before making recommendations.
"The truth is there are
different types of hips and different types of patients," said Dr. William Maisel, FDA's chief scientist
for devices, in an interview last week. "Understanding the
characteristics of patients who experience adverse events is very
important."
Women and overweight people are among the groups that are more
likely to have an implant failure.
With little definitive data on U.S. hip implants, the agency has asked
manufacturers like Johnson & Johnson, Zimmer Holdings Inc. and Biomet Inc.
to conduct long-term, follow-up studies of more than 100 metal-on-metal hips on
the U.S. market.
FDA scientists say the studies will
help "fill in the blanks" on a number of scientific questions,
including the long-term effects of metal particles.
But public health advocates say it could take a decade before
that information is available.
"Keeping these metal-on-metal hips on the market for the
next five to 10 years while research is conducted is not ethical," said
Diana Zuckerman, president of the National Research Center for Women &
Families, during a public comment session at the meeting. "If the
companies want to sell metal-on-metal hips, they should be required to prove
their safety first."
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