Metals in medicine and surgery

Abstract

With the current widespread application of surgical implants, consideration of the effects of the human environment on the implantable materials and of the influence of the materials on the human cells and tissues has become essential. When implanted in the body, all implantable materials undergo chemical or electrochemical dissolution at some finite rate which may alter appreciably with time. Also, the human environment imposes mechanical forces upon surgical implants, usually of low magnitude and high frequency of application. In this review, the tendency of implantable materials to undergo mechanical, chemical, electrochemical, and mechanicochemical failure is described. The results of available accelerated laboratory tests on specimens studied under conditions that simulate those in the human body are compared with observations on implants after their removal from humans and experimental animals. The potentially deleterious side-effects of implant dissolution on adjacent and distant tissues such as tissue toxicity, hypersensitivity, altered resistance to infection, hypercoagulation of the blood, and malignant transformation are described. Also, the effects of mechanical forces imposed by implants on adjacent tissues are discussed. Finally, the primary goals for future research on implantable materials and surgical implants are outlined.