Metal ions release from metallic orthopedic implants exposed to tribocorrosion and electrochemical corrosion conditions in simulated body fluids: Clinical context and in vitro experimental investigations

Abstract

The use of metallic biomaterials in the medical implant devices has become increasingly prevalent over the past few decades. Patients find themselves being exposed to metals in a variety of ways, ranging from external exposure to instruments such as medical devices to internal exposure via surgical devices being implanted in their bodies. Potential health risks are associated with metallic wear debris in the form of nanoparticles in situ generation and the release of in vitro metal ions into human biological specimen's circulation. In combination with mechanically accelerated electrochemical processes, this can lead to the release of toxic metal ions, nanoparticles or micro scaled debris in the surrounding tissues and body fluids bring about relevant health issues and contribute to implant loss of failure. Metal ions release from metallic materials; stainless steel, cobalt-chromium alloys, titanium and its alloys, and nickel-titanium alloys implanted into the human body in orthopedic surgery is becoming a major cause of concern. The degradation mechanisms of the metallic implants lead to implants failure and tissue inflammation. However, the levels of metallic ions in those fluids can vary depending on the involved degradation mechanism of the implant. After briefly recalling the clinical context, this article analyses the in vitro studies on metals and metallic alloys corrosion, tribocorrosion and electrochemical corrosion under simulated inflammation conditions. Specifically, the present review reported the results of in vitro experimental investigations on the release of metal ions from metallic orthopedic implant materials, subjected to different electrochemical corrosion and tribocorrosion conditions, into simulated human body fluids.