BMJ: Metal-on-Metal Hip Replacements a "Large Uncontrolled Experiment"

Akron, OHWhen consumers think of leaking implants, they tend to think of breast implants, not DePuy hip replacements. But according to reports, some experts are concerned that the DePuy ASR, which was subject to a massive DePuy hip implant recall in 2010, could cause more damage than breast implants.

According to the British Medical Journal and the British Broadcasting Corporation (cited by Bloomberg; 2/28/12), metal-on-metal hip replacements such as the DePuy hip implants could cause harm to more patients than the leaking breast implants that were the focus of so much press in recent years. In a statement released in February 2012, the BMJ and BBC speculated that hundreds of thousands of people around the world may have been exposed to metallosis, a condition in which high levels of toxic metals seep into the patient's system.

Such leakage of toxic debris from the hip implant into the patient's tissue and bones can cause destruction of the tissue and bones, and result in the hip implant failing prematurely. Furthermore, there are some indications that once the metal debris is in the tissue, it can spread through the bloodstream to the liver, kidneys and other organs, causing further health problems.

Johnson & Johnson and its subsidiary, DePuy Pharmaceuticals, announced a recall of the metal-on-metal hip implants in August 2010, after reports surfaced that the implants were failing prematurely. According to the National Joint Registry of England and Wales, the DePuy ASR Acetabular implant had a revision rate of 29 percent, compared with less than 10 percent for all metal-on-metal implants. Meanwhile, the Medicines and Healthcare products Regulatory Agency recommended that doctors conduct annual MRI scans for the life of certain implants.

According to the article in BMJ (2/28/12), written by Deborah Cohen, "Despite the fact that these risks [associated with toxic substances from hip devices] have been known and well documented for decades, patients have been kept in the dark about their participation in what has effectively been a large uncontrolled experiment."

Perhaps most damaging, however, is the argument that manufacturers of metal-on-metal hip devices knew that there was the potential for genotoxicity. According to the joint BMJ, BBC report, an internal DePuy memo expressed concern that "wear debris [from hip implants] may be carcinogenic." The memo further noted, "One study suggested a threefold risk of lymphoma and leukaemia 10 years after joint replacement," before concluding that the ultimate test is the "long term human experience."