The integrity of metal-on-metal hip replacement systems has been a topic of significant concern to regulatory agencies around the globe. The increasing number of adverse health events associated with the surgical implantation of these devices suggests an escalating risk that must be dealt with accordingly. As a result, officials at the U.S. Food and Drug Administration (FDA) have announced that they will be holding a two day meting in order to determine the safety and efficacy of metal-on-metal hip replacement systems. Of significant concern, however, is the lack of data required to make important regulatory decisions. According to several prominent healthcare professionals, the FDA may not have the information it needs to make a definitive decision for another decade.
For decades, the majority of orthopedic components were made from plastic or ceramic materials. However, the last 10 years have witnessed many surgeons began to favor those made of metallic components. According to laboratory tests, metal implants demonstrated an increased resistance to wear and tear, therefore reduce the chance of dislocation. Eventually, metal-on-metal hip replacement systems became the preferred method of corrective measures.
Metal-on-metal hip replacement systems consist of a series of metallic components (cobalt and chromium) in order to promote longevity and dexterity. Their soul purpose is to allow their recipient to regain the functionality in their hip that had recently been lost. In replacing compromised hip joints with that of a metal stem and socket, patients were rewarded with an increased mobility that had previously been unavailable without pain and suffering.
Unfortunately, however, recent evidence suggests that metallic components consisting of cobalt and chromium may coincide with catastrophic complications in defective hip replacements. More specifically, the wear and tear that ball and socket components generate may lead to significant deterioration over a seemingly short period of time. This degeneration has a tendency to create minute metal shavings that have the potential to cause significant damage to an individual. As a result, these metal pieces may lead to a concentration of hazardous metal shards in the fluid of the joint and surrounding muscles that can cause extreme pain and swelling when leached into the recipient. The FDA received 16,800 negative event reports involving metal hips between 2000 and 2011.
According to British experts, hip replacements are supposed to last approximately 10 to 15 years, yet more than six percent of the recipients needed them replaced after less than five years. Subsequently, those with ceramic or plastic joints only exhibited a two percent failure rate. In light of these findings, the British experts at the world’s largest artificial joint registry tried to convince doctors to stop using metal-on-metal hip replacements. However, those that have already received metal implants were recommended to get yearly blood tests to make sure they were not experiencing any adverse effects.
In response to the influx of adverse events reported by the recipients of metal-on-metal hip replacement systems, the FDA has decided to hold a two-day meeting to scrutinize the safety of such implants. The results of the meeting will undoubtedly have an overwhelming affect on the estimated 500,000 Americans who have already had the devices implanted. At the meeting, officials will review combined data from foreign countries and the U.S. to determine which groups of patients and implants are most problematic.
“Why look at a single registry when there’s data from around the world?” said Dr. William Maisel, FDA’s chief scientist for medical devices, in an interview with the Associated Press. “This is an opportunity for us to look at all the available information so that we can have a thoughtful conversation about what clinical recommendations can be made.”
In association with reviewing data from around the world, the FDA has also asked Johnson & Johnson, Zimmer Holdings Inc. and Biomet Inc. to conduct long-term, follow-up studies of more than 100 metal-on-metal hips on the U.S. market. According to FDA officials, research such as this should provide the healthcare community with better insight to the safety and efficacy of the devices.
Unfortunately, however, research such as this will take time. Experts believe it could take a decade or more for the follow-up studies to produce meaningful results. In a commentary published last week in the New England Journal of Medicine, researchers pointed out that a study such as this must run at least eight years to return the information the FDA is seeking. While it will be a long time before follow-up studies produce results, the meeting that is set to convene this week is a step in the right direction of determining the safety of these products.