All-Metal Hip Replacements Riskier, No Advantage Over Older Implants: Study

According to the findings of a new federally-backed study, all-metal artificial hip replacements appear to carry a greater risk of problems, yet provide no advantage when compared to older types of hip implants. 

FDA researchers published a report in the British Medical Journal on November 29, which examined the effectiveness of a number of types of hip implants, including metal-on-metal hip implants, as well as ceramic-on-ceramic implants, and compared them to older metal on polyethylene implants and ceramic on polyethylene implants.

The study found that there is no advantage to metal-on-metal hip implants over older designs using other materials. However there have been a number of problems with all-metal hip replacements identified in recent years, which may expose patients to a risk of early failure and the need for revision surgery.

As the metal parts rub against each other, microscopic shavings of metal can be released into the tissue surrounding the implant, resulting in a condition known as metallosis.

Concerns about the safety of all-metal implants increased in 2010, after a DePuy ASR metal hip recall was issued due to higher-than-expected failure rates. More than 90,000 of the recalled implants were sold worldwide before the problems were acknowledged by the manufacturer, and hundreds of individuals in the United States have filed a DePuy ASR hip lawsuit after experiencing complications with the implant.

There are also an increasing number of lawsuits involving the DePuy Pinnacle hip system, another metal-on-metal hip implant by the Johnson & Johnson subsidiary DePuy Orthopaedics.

A number of other artificial hip manufacturers also make all-metal implants, which have also been the subject of product liability lawsuits.

The FDA comparative study looked at 3,139 patients in 18 comparative studies with data from more than 830,000 operations in national registries worldwide. The researchers found that metal on metal hip implants were associated with higher occurrence of revision when compared with metal on polyethylene on national implant registries in Australia, New Zealand and England. Three smaller registries, including the U.S. Center for Medicare and Medicaid Services (CMS) did not detect a difference in revision rates.

“Evidence on implant revision did not favor metal on metal implants,” the FDA researchers wrote. ” There is limited evidence regarding comparative effectiveness of various hip implant bearings, and the results do not indicate any advantage for metal on metal or ceramic on ceramic implants compared with traditional bearings.”

In May 2011, the FDA asked device manufacturers to obtain more information about the level at which the metal particles shed by hip replacements becomes dangerous, how much metal they actually shed and what the potential side effects of metallosis are.