Metallic Medical Implants: Electrochemical Characterization of Corrosion Processes

The use of metallic alloys for medical implants is supported by their superior mechanical properties such as hardness and stiffness, alongside benefits like biocompatibility and visibility in X-ray imaging. However, electrochemical reactions that occur on metallic surfaces in vivo pose significant challenges. To address this, in vitro reactivity characterizations are critical for understanding degradation processes and improving new implant materials. This study investigates corrosion susceptibility through various macro- and micro-electrochemical methods, revealing the complexity introduced by physiological media containing proteins and cells. The study emphasizes the necessity to examine degradation mechanisms influenced by solution chemistry, temperature, and atmospheric conditions, particularly in the presence of chloride ions which can cause localized corrosion associated with implants' microstructures. Additionally, the formation of a native anodically grown oxide layer on metallic surfaces, while offering uniform corrosion resistance, can succumb to localized breakdown under aggressive conditions. The research highlights the simultaneous occurrence of different corrosion types, such as crevice corrosion due to complex implant geometries and galvanic coupling between dissimilar materials. These findings underscore the need for extensive experimental approaches to effectively address the corrosion challenges related to metallic implants.