February 26, 2015 - Could a Simple Test Detect Metal Sensitivity Prior to Metal Hip Implantation?
A 2012 article on Drugs.com noted that testing patients to determine whether they were especially sensitive to metals prior to receiving a metal hip implant could significantly cut down on the complications which arise from metal hypersensitivity. Although cobalt and chromium ions in the body can be dangerous for all patients, those who have metal hypersensitivity can suffer even more. In a study which included 72 patients, thirty-one of those patients underwent skin patch testing for metal hypersensitivity prior to receiving their implant while the other forty-one were tested after they received a metal implant. In the pre-implantation group, 21 of the 31 patients reacted to a single metal, while 15 of the 31 patients reacted to multiple metals.24
Surgeons used an implant which was not constructed of metal for those patients who tested positive for metal sensitivity, and none of those patients developed skin rashes or early joint loosening. Among those in the post-implantation group, the patients with positive reactions to metals were much more likely to experience symptoms of metal toxicity and metallosis after their metal hip implant, including chronic pain at the implant site. Six of the patients had their metal implant removed, and their symptoms ceased, while the patients who did not have their implants removed saw their symptoms continue, and increase. It is a worthwhile goal to identify patients who would benefit from a non-metal hip implant.
Hip Replacement Safer Than Hip Resurfacing?
A study published in the Journal The Lancet was reported on Drugs.com claims women in particular should steer clear of hip resurfacing and that the procedure fails in many patients when compared to hip replacement. Hip resurfacing is often recommended to younger, more active patients. The procedure for hip resurfacing is similar to total hip replacement, however the femoral head is not completely removed. Part of the femoral head—the round top section of the thighbone—is removed, and a metal cap replaces the removed bone. Metal-on-metal bearings are always used in hip resurfacing, hip replacements may implement ceramic, metal or polyethylene bearings.
Data collected in England and Wales over a period of eight years included more than 434,000 hip operations. Resurfacing implants were found to fail more quickly and the use of smaller femoral heads sizes also increased the rates of hip failure. Hip resurfacing in women had failure rates up to five times as high as other bearing surfaces. The Lancet study also objected to the manufacturers using the term “young and active,” stating that “few patients, even if elderly and inactive, will refuse a device that is intended for the young and active.”25
Caution by Canadians Resulted in Fewer Metal Hip Problems
While American surgeons and patients embraced metal hip replacement devices wholeheartedly once they began being aggressively marketed by the manufacturers, Canadian surgeons weren’t quite so quick to jump on the metal-on-metal bandwagon. Dr. Michael Dunbar, an orthopedic surgeon and co-chair of the joint replacement registry in Canada stated, “It was the right side of the street to be on, for sure.”26 Dunbar noted that the number of all-metal hip implants in Canada remained low, even though at the highest points, almost 45% of all hip implants done in the United States was with a metal-on-metal device. Unlike the United States, Canada also tracks patients’ hip implants through a voluntary registry. At least three out of every four hip replacements in Canada are metal-on-plastic devices which show a much lower rate of problems than the metal-on-metal implants.
Johnson & Johnson to Halt Sales of Metal-on-Metal Hips
In May of 2013, Johnson & Johnson announced it would no longer be selling metal-on-metal hip replacement devices.27 A spokesman for the company claimed the decision was not due to the thousands of lawsuits against Johnson & Johnson and DePuy regarding the recalled ASR, rather based on the waning demand for the devices as well as new rules sought by U.S. regulators. Johnson & Johnson stated the metal liners for the Ultamet metal-on-metal and the Complete ceramic-on-metal hip systems will no longer be available after August, 2013.27 Sales of metal-on-metal hip implant devices in the United States and in Europe plummeted from 20% of the market to less than 2% in 2012.