Yet Another Metal-on-Metal Hip Implant Study Links Devices to High Rate of Early FailuresMar 13, 2012 | Parker Waichman LLP
It seems that bad news regarding the safety of metal-on-metal hip implants comes out on a weekly basis. This week is no different, with a study published today in The Lancet reporting that people with metal-on-metal hip implants are twice as likely to experience early failures compared to those fitted with implants made with other materials, such as ceramic-on-ceramic and metal-on-plastic. The Lancet study will only add to growing concerns that metal-on-metal hip implants could be shedding dangerous amounts of metal debris into patients' blood streams, leading to serious health risks, including tissue damage, disability, and possibly cancer.
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. Another 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.
According to the Lancet study, which was conducted by researchers at the University of Bristol in the U.K., 6.2 percent of all-metal hip implants patients need a second operation in five years. Failure rates were as much as four times higher in women, who are likelier to have implants containing a larger prosthetic femoral head. 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.
The Lancet study is being called the most comprehensive to date. In reaching their conclusions, the article's authors 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. That device registry is the largest in the world.
Not surprisingly, the Lancet researchers have added their voices to those calling for a ban on metal-on-metal hip implants.
“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.”
Just last week, the British Hip Society called for an end to the use of all-metal hip implants with larger femoral heads (36 mm or higher) in total hip replacement. Just prior to that, U.K. device regulators advised that patients with the larger metal-on-metal hip implants yearly blood tests check cobalt and chromium blood levels in some all-metal hip implant recipients. Those who do exhibit high metal ion levels should be subjected to MRI to check for damage near the implanted joint, the agency said. 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.