The debate as to whether or not metal-on-metal hip replacement systems provide their recipients with a positive risk/benefit profile has plagued the medical device industry for years. Unfortunately, however, the current debate may be nearing its final days. According to cumulative data collected from foreign registries, metal-on-metal hip replacements exhibit an increased propensity for failure beyond that of older implants. Subsequently, the U.S. Food and Drug Administration (FDA) has officially announced that there are few reasons to continue using metal-on-metal hip implants, due to the influx of data suggesting that the devices can break down early and expose patients to dangerous metallic particles.
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 reducing 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, metal-on-metal hip replacements have become the subject of great concern. Recent evidence suggests that the metallic components may be prone to failure in defective hip replacement systems. Accordingly, 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 the development of metallosis. Metallosis witnesses the leeching of hazardous metal shards into the fluid of surrounding tissue. The resulting damage may lead to severe pain and even the death of localized tissue.
In response to the recent influx of complications regarding metal-on-metal hips, officials at the FDA held a meeting to discuss their safety and efficacy. During the meeting, the FDA asked its 18-member panel to recommend guidelines for monitoring more than a half-million U.S. patients who had already received metal hip replacements. In doing so, healthcare regulatory agencies around the world hoped to better understand these ambiguous devices.
While a recall has yet to be made, the majority of the panelists acknowledged that there were very few incidents, if any, that would cause them to recommend surgically implanting a metal hip replacement system into a patient. “I do not use metal-on-metal hips, and I can see no reason to do so,” said Dr. William Rohr of Mendocino Coast District Hospital, who chaired the meeting.
Reasoning behind the panels distain for metal-on-metal hip replacements can be found in the cumulative data of several foreign registries. According to the data obtained from foreign healthcare regulatory agencies, these devices fail at a higher rate than that of the older plastic and ceramic implants. Subsequently, older devices have proven to be just as effective as their metal predecessors.
Regardless of this evidence, U.S. regulators have acknowledged that they need more time to make an accurate decision. There are too many variables to consider when determining the safety of these devices, and officials want to make sure they get it right. “The truth is there are different types of hips and different types of patients,” said Dr. William Maisel, FDA’s chief scientist for devices, in an interview last week. “Understanding the characteristics of patients who experience adverse events is very important.”
In an attempt to better understand the safety of metal hip replacements, the FDA has requested the help of several manufacturers. Industry leaders such as Johnson & Johnson, Zimmer Holdings Inc. and Biomet Inc. have agreed to conduct long-term, follow-up studies of more than 100 metal-on-metal hips on the U.S. market. Doing so may help regulatory agencies understand the long-term effects of these devices.
However, officials at the FDA have suggested that such an extensive follow-up study may take nearly a decade to complete. To many, that time frame is too long to wait to determine the safety of these devices. “Keeping these metal-on-metal hips on the market for the next five to 10 years while research is conducted is not ethical,” said Diana Zuckerman, president of the National Research Center for Women & Families, during a public comment session at the meeting. “If the companies want to sell metal-on-metal hips, they should be required to prove their safety first.”