[The hard lesson of metal-on-metal hip implants]

Metal-on-metal hip implants with a large metal head (≥ 36 mm) have shown periprosthetic adverse soft tissue reactions and high blood concentrations of metal ions in patients. This has raised concern that exposure to metal ions may induce complications and could increase the risk of cancer. In view of the present level of uncertainty and for reasons of patient safety, the Dutch Orthopaedic Association (NOV) has advised its members to suspend utilisation of all metal-on-metal hip implants with a large head (≥ 36 mm) until the safety and long-term effectiveness have been established. All patients with these implants will be invited for an annual check-up according to a set protocol. This outpatient examination will also include assessment of cobalt ion levels and X-ray diagnostics. Based on the blood concentration of cobalt, the clinical status and the X-ray, the patient will be advised to undergo a revision procedure of the implant.