Changes in nonosseous tissue adjacent to titanium implants

Abstract

Abstract A combined histological, metallurgical, and clinical study has been made in 19 instances where a surgical operation had been performed to remove a titanium implant used in the treatment of disease or trauma in man. All the implants were static devices such as pins, plates and rods. Histological examination of nonosseous tissue excised from adjacent to the implant was supplemented by estimation of its titanium content by neutron activation analysis. The results indicate that in some patients titanium can be liberated into tissue adjacent to titanium implants. The phenomenon can occur in the absence of corrosion or fracture of the implant, and is unrelated to the possible liberation of wear particles from an artificial articular surface. There is variation from individual to individual in the amount, if any, of titanium released. In the case of those implants showing titanium release, the results suggest that local release of the metal, or its subsequent accumulation in the tissue, is a patchy process at the implant site. The histological features of the local reaction of nonosseous tissue to titanium release are described. No conclusions have been drawn concerning possible effects on the osteogenic response to the insertion of the implants and on the overall state of the bone at the time of their removal. From study of the clinical records it is apparent that considerable caution is needed before concluding that release of titanium can cause clinically significant local effects. Although such effects may have occurred in a minority of patients, this possibility is by no means proven. A distinction must be drawn between a “metal reaction” in the histological sense and a “metal reaction” in the clinical sense.