Health Canada has warned the country's surgeons not to implant zirconia ceramic femoral heads until the source of manufacture can be ascertained. The warning involves ceramic heads made by a French company, Saint-Gobain Advanced Ceramics Desmarquest, since 1998. It was issued because of an increased rate of spontaneous fracture after implantation. Femoral heads made by other companies are not affected by the recall. Physicians are asked to report any cases involving this type of fracture to the Medical Devices Problem Reporting Hotline, 800 267-9675.