Clinical and Metallurgical Observations on the Corrosion of Stainless Steel Screws used in Orthopædic Surgery

Abstract

WE wish to comment briefly on the recent article by Bowden, Williamson and Gowans Laing1 in which they direct attention to the transfer of metal from the screw-driver to the head of an orthopaedic screw. While we are completely convinced by their experimental work on metallic transfer, we doubt the importance of this particular effect in promoting electrolytic corrosion of orthopaedic components. Particularly we would point out that the transfer of 65 µgm. of anodic material to the head of the screw would allow the corrosive dissolution of that 65 µgm. of material from the head of the screw, whereas clinical observation indicates that it is not the screw head which suffers the most serious corrosion. With stainless steel material the significant destructive corrosion, as distinct from superficial tarnishing, is concentrated at regions of contact between two metal components or between metal and bone. Moreover, in certain cases, as much as 1 gm. of metal may be dissolved away from one nut or screw. Corrosion at such regions obviously destroys the mechanical rigidity of the fixation. A more detailed account of the theory of the distribution of destructive corrosion in orthopaedic screws is in course of preparation.