Metallic materials used for implants have a passive layer which protects the surface from the leaching out of metallic ions. Co, Cr and Ti ions have been found to show cytotoxic effects when the levels reach significant concentrations. Ion levels in the tissue result in cell death by necrosis and apoptosis, the rate of which is influence by ion concentration. The presence of dying cells can eventually stimulate inflamation and rejection of orthopedic implants.
