Risk of Cancer with Metal-on-Metal Hip Replacements Not Seen: Study

According to the findings of a new study, researchers were unable to find any signs of an increased risk of cancer over the first seven years after patients receive a metal-on-metal hip replacement, which is known to shed microscopic metal particles into the blood stream that may cause the formation of tumor-like growths among some patients.  

The UK National Joint Registry (NJR) presented its annual report (PDF) at the British Orthopaedic Association Annual Congress in Manchester on September 13, highlighting a study that found no correlation between cancer and all metal hip replacements, which feature a metal ball that rotates within a metal acetabular cup.

Researchers looked at 80,314 hip replacement procedures performed in 2011. Of those, 8,641, or 11 percent, were revision surgeries where the artificial hip had to be removed. That rate was about the same as 2011, researchers noted.

Many of the revision surgeries involved patients suffering from metal blood poisoning, also known as metallosis, which is known to occur as the metal components rub against each other. Patients have reported suffering pseudotumors and necrosis of the tissue around the implant, which are believed to be caused by high cobalt and chromium levels in the blood.

As a result of the problems with metal-on-metal hip replacements, concerns have emerged that individuals may face an increased risk of cancer the longer the artificial hips remain in place. However, researchers indicate that early data does not show that as likely.

The findings may provide little piece of mind for individuals who received a metal-on-metal hip replacement in recent years, as the implant design has still been linked to a high rate of early failure, often resulting in the need for revision surgery within a few years due to metallosis and loosening of the implants.

Sales of metal-on-metal hip replacements have fallen sharply over the past two years, and more research has been focused on the impact of these microscopic particles entering the blood stream since a recall was issued for DePuy ASR hip implants in August 2010.

The Johnson & Johnson subsidiary Depuy Orthopedics issued an ASR hip recall after acknowledging that 12% to 13% of the implants were found to fail within the first five years.  Since that time, thousands of DePuy ASR hip lawsuits have been filed against the manufacturer alleging that they failed to adequately research the design or warn about the risk of failures.

Similar product liability lawsuits have also been filed over other metal-on-metal implants, including the DePuy Pinnacle hip, Biomet M2A-Magnum hip and Wright Conserve hip.