Stress corrosion cracking of bone implants

A diagnostic investigation has been carried out on some AISI type 316 stainless steel fixation nails that failed during service in the recovery treatment of femoral fractures. The association of pitting and cracking at the nail edges where the cracking process appears to start together with fractographic features of the ruptured surfaces has led to the belief that pitting in crevice-induced stress corrosion cracking from acid chlorides is the cause of failure. In this respect, consideration should be given to the new high-Cr ferritic stainless steels, extra-low in interstitial elements, which are much more resistant than ordinary austenitic grades to pitting and s.c.c. in chloride media.