Modern, all-metal hip implants appear no more effective than traditional implants and may be less safe, according to a new report, a finding that could hurt the device makers and accelerate lawsuits.
The report, published on Tuesday in the British Medical Journal, found that patients who received so-called metal-on-metal implants were more likely to require repeat surgery than those who received traditional implants.
Every year, more than 700,000 joint replacements are performed in the United States, of which some 270,000 are hip replacements, according to the report.
The materials used in a replacement hip's ball-and-socket structure can include metal, ceramic or plastic. Metal on metal implants were supposed to be more durable than earlier metal on polyethylene implants. But over the past few years, reports have emerged that the metal implants fail at a greater rate than traditional implants.
Last year, Johnson & Johnson's DePuy Orthopaedics Inc unit recalled its metal ASR hip system after it failed at a higher-than-expected rate. Some patients experienced pain, swelling, joint dislocation and even systemic damage caused by toxic levels of metal ions.
The latest report, sponsored by the U.S. Food and Drug Administration and conducted in conjunction with academic experts, reviewed all published literature, as well as large orthopedic registries to come up with the most comprehensive overview to date.
Lead author Dr. Art Sedrakyan of Weill Cornell Medical College in New York City said that while the analysis is preliminary, it indicates that patients implanted with a metal-on-metal device are doubly at risk of requiring a repeat procedure.
U.S. regulators have asked companies that make metal-on-metal implants for more information about their safety. Manufacturers include Zimmer Holdings, DePuy, Wright Medical, Biomet and Smith & Nephew.
"There's more work needs to be done before drawing more definitive, worldwide conclusions, but it is probably not likely to change the signal that these metal-on-metal implants are failing at a greater rate," Sedrakyan said.
The report analyzed the results of 18 studies involving 3,139 patients and more than 830,000 operations reported in registries.
The analysis found that no difference was observed in functions such as the ability to carry out daily activities between patients with the metal-on-metal implants compared with the older implants.
Sedrakyan said that patients who are about to receive a metal-on-metal hip implant should ask their doctor for a full explanation as to why this type of hip is needed.
SOURCE: bit.ly/vz2aB7 BMJ, November 29, 2011.