Yet another study is raising questions about the benefits of newer hip and knee replacement devices, including metal-on-metal hip implants. According to a report in The New York Times, the study, based on data from Australia’s orthopedic registry, showed that not one artificial hip or knee introduced over a recent five-year period was any more durable than older ones. What’s more, close to 30 percent of the new devices performed poorly compared to older implant models.
The Australian study appears in the Journal of Bone and Joint Surgery, the Times said. Its authors analyzed data for all new hip and knee prostheses brought to market between January 1, 2003, and December 31, 2007, and used on at least 100 occasions. That analysis was compared to combined results of the three best performing established hip and knee prostheses with a minimum duration of follow-up of five year.
The analysis found that of the new devices used in a sufficient number of procedures, 27% (nine of thirty-three) of the hip replacements and 29% (eight of twenty-eight) of the knee replacements had a significantly higher rate of revision than the older devices. None of the newer prostheses had a lower rate of revision than the established prostheses. The study authors concluded that there was “no benefit to the introduction of new prostheses into this national market during the five-year study period.”
According to The New York Times, the findings hold important implications in the U.S. because many of the new devices, such as metal-on-metal hip implants, are widely used here. Already, metal hip implants are the subject of serious concerns, as it is expected that they will fail prematurely in thousands of patients. Metal-on-metal hip implants include DePuy Orthopaedic’s ASR hip implant, which was recalled in August 2010 because of a higher-than-expected early failure rate. Other all-metal hip replacements that have been the subject of complaints include the all-metal version of DePuy’s Pinnacle hip implant system.
As we’ve reported previously, it is believed that metal-on-metal hip implants can shed dangerous amounts of cobalt and chromium through wear, leading to tissue damage, premature device failure, the need for revision surgery, and even long-term health problems. In May, the U.S. Food & Drug Administration (FDA) directed 21 makers of all-metal hip implants, including DePuy, Zimmer, Stryker, Biomet and Wright Medical, to conduct post-market studies of their devices to determine if they were shedding dangerous amounts of metallic debris in patients.
Just last month, a study of hip implants commissioned by the FDA found that new versions, including all-metal designs, offered no benefits over older types of implants. It also found that people who received all-metal hip implants were more likely to require repeat surgery than those who received traditional implants.