Another study has confirmed that metal-on-metal hip implants are more likely to fail compared to other types of hip replacement devices.
The Lancet Study is being called the most comprehensive to date, according to a Reuters report. Researchers at the University of Bristol in the U.K. analyzed data from the National Joint Registry of England and Wales covering more than 400,000 hips replacements, including 31,171 all-metal ones, that occurred between 2003 and 2011. They found that people with metal-on-metal hip implants were twice as likely to experience early failure of their device compared to those fitted with other types of implants.
According to a report from Bloomberg News, 6.2 percent of all-metal hip implants patients need a second operation in five years. The study also found that larger metal hips failed sooner — each 1-millimeter increase in femoral head diameter corresponded to a 2 percent increase in the risk of failure. Finally, failure rates were as much as four times higher in women, who are likelier to have implants containing a larger prosthetic femoral head.
“Metal-on-metal stemmed articulations give poor implant survival compared with other options and should not be implanted,” the study authors wrote. “All patients with these bearings should be carefully monitored, particularly young women implanted with large diameter heads.”
The Lancet study is just latest to point to serious health risks associated with all-metal hip implants. Just last month, the U.K.’s Medicines and Healthcare Products Regulatory Agency (MHRA) announced that blood tests should be conducted yearly to check cobalt and chromium blood levels in some all-metal hip implant recipients, those with bearings of 36 mm or above. Those who do exhibit high metal ion levels should be subjected to MRI to check for damage near the implanted joint, the agency said. Only last week, the British Hip Society advised that larger metal hip implants be used in total hip replacement surgery.
Late last month, the British Medical Journal revealed that metal-on-metal hip implant manufacturers were aware of mounting evidence linking metal-on-metal hip replacement devices to serious, long-term health consequences, but for years failed to warn the public about these dangers.
Last May, the U.S. Food & Drug Administration (FDA) directed 21 companies that market all-metal hip replacement devices to conduct post-market studies of their products to determine if they were shedding dangerous amounts of metallic debris in patients. The shedding of metal debris may cause tissue damage, the development of cysts and pseudotumors, premature device failure, the need for revision surgery, and other long-term health problems.
Metal-on-metal hip implants include DePuy Orthopaedics’ ASR Hip Resurfacing System and the DePuy ASR Acetabular System, which were recalled in 2010 because of an unusually high premature failure rate. DePuy, a division of Johnson & Johnson, currently faces more than 5,000 U.S. lawsuits over its defective ASR hip implants. At least 900 lawsuits are pending in the U.S. over an all-metal version of its Pinnacle hip replacement device, with plaintiffs claiming it is similar in design to the ASR implants and should have been recalled as well.
