Patients who have received a total hip arthroplasty (THA) with a metal-on-metal hip implant will most likely need a replacement within 10-13 years after they have been implanted. In a study published in June of 2015, researchers found that 1 in 5 patients will experience a failed metal-on-metal hip implant far before hip implants made from other materials will fail.
James Drummond of Melbourne Medical School at the University of Melbourne in Australia, Phong Tran and Camdon Fary from the Department of Orthopaedics at Western Health in Melbourne, Australia, have found joint registry data from 2008 that showed an alarming number of revision rates, which prompted them to research further into metal-on-metal hip replacements and resurfacings. The researchers found that adverse reactions to metal wear debris “can cause significant damage to soft tissue and bone” if it isn’t discovered early enough, and “can cause soft tissue changes in the surrounding tissues,” which are lesions known as “pseudotumours.” The researchers also found that hip implants with larger heads had a much higher risk for early failure.
According to the study, a recent systematic review examined the blood test results from nearly 10,000 patients that had received a metal-on-metal hip implant. The results showed that the patients had metal ion concentrations “consistently higher” than previous blood tests performed immediately following the hip replacement. The cobalt and chromium metal ions were particularly alarming.
The outcome of revision surgeries for patients experiencing inflammatory pseudotumours doesn’t look good. The study revealed a shocking 50 percent of these patients encountered major complications and a third of them required yet another revision. The study pointed out that a small case study reported 68 percent of patients that had revision surgery following implantation of a Durom metal-on-metal THA because of adverse reaction to metal debris experienced complications.
The study concluded that “Early diagnosis of adverse reactions and appropriate treatment for failing prostheses is essential for limiting the extent of soft tissue destruction and osteolysis that can occur as a result of adverse reactions to these implants.”