Researchers have a better understanding of why patients often suffer from inflammation and other long-term, chronic illnesses after being implanted with artificial hip devices made from all metal parts, such as the ASR hip implants recalled by DePuy Orthopaedics in August 2010.
Researchers from Ohio State University and Imperial College London have combined high-resolution X-ray technology and electron microscopy to study the inflamed tissue surrounding the metal-on-metal hip devices implanted in patients. Their study, published in the journal Chemical Communications, found that inflammation occurs when Cobalt2+ ions are shed by the cobalt-chromium implants into the surrounding tissue.
Previous studies have found Co2+ ions to be “genotoxic,” meaning they have the potential to harm metal-hip-implant recipients at the DNA level, causing possible long-term and permanent medical complications.
According to Imperial College London, the study “is one of the first to look at the effects of nano-particles in humans and raises questions about how materials are tested before they are used as implantable materials.”
“We were able to meet patients who had these failing implants and we could see first-hand the chronic inflammation, pain and loss of mobility they experienced,” Dr. Mary Ryan of Imperial College London and co-author of the study, said. “Even though a huge number of patients have benefited from replacement surgery, we still don’t fully understand the long-term impacts that implantable materials have on our bodies. Our work is one of the first to study these nanoparticles and the effects that they have on damaged cells and tissue. This has enabled us to understand in much more detail the side effects that these materials may have in patients.”
According to Imperial College London, the researchers found that the nanoparticles from the implants accumulated in the white blood cells, where they undergo a corrosion process, dissolving rapidly and entering the bloodstream as well as the surrounding tissue. Larger, less soluble chromium particles formed a “solid residue” that remained in the tissue.
Concern over the use of metal-on-metal hip implants has grown steadily ever since DePuy announced it was recalling its ASR XL hip replacement and resurfacing systems. The recall was prompted by studies that showed the metal hips were failing at alarmingly high rates and potentially injuring patients. More than 93,000 people worldwide had been implanted with one of the recalled hip devices before DePuy recalled them.
Image courtesy Zephyris at English language Wikipedia
Imperial College London