SCENHIR, the European Union’s Scientific Committee on Emerging and Newly Identified Health Risks, has issued an opinion on the safety of metal-on-metal (MoM) joint replacement devices, with “particular focus” on hip implants.
The committee examined concerns over possible exposure to cobalt and/or chromium after MoM-hip resurfacing or replacement that can lead to organ toxicity, carcinogenicity and teratogenicity (malformation of the fetus).SCENHIR recommends an annual follow-up for the life of the joint for patients with large-head devices. Hip-replacement patients with special risk factors like small component size, female gender, or low coverage arc should have an annual follow-up for the lifetime of the joint. All patients should undergo clinical and radiographic examination during follow-up. Metal ion testing is recommended for patients with large-head MoM hips on a routine basis and for hip resurfacing patients in the first postoperative years and thereafter depending on the devices’ performance.
SCENHIR concluded that the use of MoM devices should be “carefully considered on a case-by-case basis, due to the potential adverse effects of released metal.” MoM implants are “contraindicated” in women of childbearing age and should not be used in females with small femoral head size. The choice of implant type should be based on a “detailed case-by-case evaluation, which takes into account all risks and benefits.” The committee recommends a “stepwise” introduction of new implants types, even those similar to devices already on the market. The committee recommends setting up mandatory national registries for all permanent joint implants.
MoM hip implants have had higher than expected early failure rates—in the first five years after implantation—and high rates of injuries and complications from metal debris shed by the devices, Consumers Union reports. Thousands of hip replacement recipients have sued device manufacturers over injuries and complications they allege are due to defective hips. Cases are pending in multidistrict litigations in a number of courts and some manufacturers have reached settlements.