Australian regulators have become the latest to issue warnings about the possible dangers associated with metal-on-metal hip implants. In a posting on the website for Australia’s Therapeutic Goods Administration (TGA), the agency advised that recipients of metal-on-metal hip replacement devices undergo regular testing, possibly on an annual basis, to check for defective hip implants and high level of metal ions in their blood.
Metal-on-metal hip implants have attracted scrutiny from regulators around the world, amid high-profile recalls of such devices and a number of studies that have raised alarms about metal hip replacement side effects. Research has found evidence that the devices can shed dangerous amounts of chromium and cobalt into patients’ bloodstream, leading to early implant failure and other metal hip replacement side effects, including adverse local tissue reactions, bone and tissue loss, and the development of pseudotumors.
Earlier this summer, the U.S. Food & Drug Administration’s Orthopaedic and Rehabilitation Devices Panel recommended that new warnings be included on the labels for such devices, and that metal-on-metal hip implant patients undergo regular monitoring to ensure their devices are not failing. Regulators in the U.K. and Canada have also recommended that patients with metal-on-metal hip implants be monitored by imaging scans and blood tests.
In its notice, the TGA acknowledged the growing body of evidence indicating that metal-on-metal hip implants can release trace amounts of chromium and cobalt, especially during the first 18-months or so after the operation. If the amount of wear is too great, then the body may not be able to excrete the extra cobalt and chromium quickly enough. In some patients this can lead to high levels of those metals in the tissues surrounding the implant. If that happens, hip or thigh pain will usually develop. High blood levels of chromium and cobalt may also be observed, the TGA said. Cobalt and chromium have been reported to be associated with problems in other parts of the body of some patients with metal-on-metal hip implants, according to the agency.
On the basis of the available evidence and on the advice of its orthopedic experts, the TGA is recommending that patients with metal-on-metal hips implants be followed up regularly (at least annually in some cases). In addition to soft tissue imaging such as ultrasound and/or MRI the follow-ups should include blood tests for cobalt and chromium. Patients who are not sure what type of hip replacement they have, or who have concerns about their device should seek information from the surgeon who performed the operation or the hospital where the operation was performed, the TGA said.