1. Experiments using radio-isotope techniques show that whenever an orthopaedic appliance is inserted into the body tiny fragments of the instruments used to handle it become detached and welded on to the surface of the buried metal.

2. There is evidence that these particles of non-passive tool-metal may cause a small but continuing dissolution of the stainless metal to which they are attached, and that this dissolution, although too small to be detected as visible corrosion, may produce an adverse tissue reaction.

3. In samples of human tissue taken from sites adjacent to buried metal the greatest level of tissue reaction and the highest concentration of iron were found near those parts of the appliances that had been handled with the tools and received the greatest amount of transferred metal.

4. Spectroscopic analyses of similar samples confirmed that the concentration of metal in the tissues surrounding a buried appliance correlates closely with the distribution on its surface of transferred tool metal. Particularly high concentrations of chromium, nickel, and cobalt were found near regions where the transfer had been heavy. The dissolution was not limited to the non-passive foreign metal; the stainless appliance was also dissolved in those regions.

5. The influence of the manner of handling the tools on the amount and distribution of transfer has been studied, and suggestions are made whereby the transfer might be reduced.