Mg-Alloy-Based Biodegradable Implants and their Corrosion Protections by Plasma Electrolytic Oxidation: An Overview

The use of magnesium (Mg) alloy as biomedical implants has garnered increased attention over the years due to its capability to progressively biodegrade in vivo, thereby avoiding the need for surgical removal of metallic implants after a complete recovery. This would, in turn, mitigate any further post-surgical and post-operative complications, reducing costs from revisional surgeries as compared to the usage of traditional metallic implants. This overview discusses the advantages that Mg-based alloys possess in biomedical implants owing to their excellent mechanical, bioactivity, and biocompatibility traits. The major limitations, mainly due to the rapid corrosive and degradative nature of Mg-based alloys in the biological environment, are reviewed comprehensively. To address the problems of Mg-based alloys for biomedical applications, the solution of plasma electrolytic oxidation (PEO) on the surface of Mg-based alloys was introduced as it could potentially help alleviate and enhance the properties of Mg-based alloys, providing improved performance in orthopedic applications. The corrosion protections can be further enhanced by combining the benefits of PEO with other biocompatible sealing layers toward practical medical applications.