Last week the FDA issued the latest safety communication regarding metal-on-metal hip implants. Prior to this safety communication the FDA had instructed the manufacturers of all-metal hip replacement systems to conduct post-market surveillance studies of the metal hip devices believing the data received from these studies would provide the necessary information regarding the safety of the implants. In June of 2012, an Orthopedic and Rehabilitation Devices Panel was convened by the FDA in order to obtain the most up-to-date scientific and clinical opinions regarding the risks of all-metal hip implants. Information from this panel contributed to the FDA’s Safety Communication and on January 17, 2013, that Safety Communication conveyed a proposed order which would require all manufacturers of MOM hip replacement systems to submit premarket approval applications.
The proposed regulatory changes seem to point to a system which will make the manufacturers of the metal-on-metal hip implants bear the burden of proving the efficacy and safety of their devices prior to placing them on the market. The FDA’s latest safety recommendations show that in some metal hip implants the metal parts rub against one another during periods of activity, resulting in the release of tiny metal particles which can find their way into the surrounding tissues or the bloodstream. Once these particles lodge in the tissues, inflammation and infection can occur, leading to tissue destruction and death and bone loss. Once the situation has reached a critical point, the implant recipient may experience total failure of the implant requiring risky revision surgery.
Should the metal ions enter into the bloodstream, metal toxicity or metal poisoning symptoms could ensue. When the metal ions build up in the body, adverse health issues can occur. Neurological, cardiovascular, renal and thyroid issues are noted side effects as well as loss of vision and hearing, gastrointestinal disorders, memory loss, vertigo, anxiety, depression, irritability and even the disruption of DNA. Of course each individual will have varying degrees of sensitivity to cobalt and chromium. Some implant recipients may have relatively low levels of these toxic metals yet are experiencing extremely serious negative health effects. Others, with higher levels of cobalt and chromium may not have yet suffered adverse effects, however as the levels of these metals continue to build, it is likely that negative symptoms will occur.
While the “normal” failure rate of hip implants is roughly 3-5%, many of the recalled all-metal hip implants have estimated failure rates as high as 40% at six years—much higher than the “acceptable” failure rates. The FDA’s Safety Communication basically wants all the manufacturers of MOM hip implants to prove the safety of their devices or pull them off the market. This Safety Communication followed a review of over 100 studies done on all-metal hip implants. The review concluded that patients who received a larger hip implant than necessary or smaller women were two groups of recipients who were likely to experience more problems with the MOM hip implants than perhaps other groups. Additionally physicians should carefully weigh the extra risks among those who are extremely overweight, patients with suppressed immune systems or those taking corticosteroids, patients with undue sensitivity to metals, those with bilateral implants, patients who are extremely active and those with renal insufficiency.
The FDA’s Safety Communication issued specific recommendations to surgeons who perform hip implant surgeries, asking that the risk vs. benefit be weighed carefully in each situation prior to implanting a metal-on-metal hip implant. Other options should be explored, including ceramic and polyethylene hip implants. The surgeon must also take into consideration the patient’s age, weight, gender, activity level and specific diagnosis before deciding on the type of hip implant device. While the FDA’s advisory panel stated that young male patients possessing large femoral heads were the best candidates for metal-on-metal hip implants, in truth this particular demographic is not one of those who normally need hip implants.
Surgeons and physicians are directed to provide every patient full disclosure regarding the risks and benefits as well as the risks of a potential revision surgery. The expectations of each patient should be addressed prior to the implant surgery as well. For those who have already undergone hip implant surgery and were implanted with a metal-on-metal device, the FDA recommends that even those who are currently experiencing no adverse symptoms undergo an annual physical exam as well as routine x-rays. The FDA makes no recommendations regarding additional blood testing and soft tissue imagine for those who are currently asymptomatic, however patients who are experiencing adverse health effects as a result of a MOM hip implant should have tests run every six months. Any recipient of a MOM hip implant should speak to their physician immediately should they experience any undue pain, worsening of any prior symptoms, or new symptoms such as swelling, numbness, squeaking, popping or grinding of the implant or any other physical pain related to metal toxicity.