Corrosion of surgical implants.

Corrosion on orthopaedic implants has been studied. Twelve intramedullary nails and twelve osteosynthesis plates were implanted up to eight and thirteen years, respectively. Analysis of biological fluids from all patients was carried out and revealed high concentrations of nickel and chromium that correlated to the implantation time. All implants were corroded by both crevice and intergranular corrosion. Intergranular corrosion is related to mechanical and heating treatments. Crevice-like corrosion is probably enhanced by sulphur present in amino-acids. Electronic probe analysis shows the reaction study between both sulphur and nickel and sulphur and chromium. These results are compared to the metal distribution in body fluids. After a certain incubation time the corrosion accelerates as is characteristic for crevice-like corrosion processes. Studies of the distribution rate of two Ni-Fe-Cr dental alloys in a cell culture system give similar results: metal-ion release increases with the exposure time.