Surface coating reduces degradation rate of magnesium alloy developed for orthopaedic applications

Magnesium (Mg) or its alloys have shown great potential as promising biocorrosive or biodegradable implantation materials and/or internal fixators, owing to their good biocompatibility and osteoinductive potential. However, poor anticorrosion property or rapid biodegradation has limited their clinical applications where initial mechanical stabilisation is required. One of the practical approaches for decreasing its biodegradation is to introduce a coating on Mg or its alloys. The current study compared the two most widely used coating techniques, i.e., microarc oxidation (MAO) and electrophoresis deposition (EPD), for coating onto the Mg–Zr pin surface, both in vitro and in vivo, to determine which method can prevent Mg–Zr alloy degradation better. In vitro pH measurement and in vivo microcomputed tomographic evaluation were used for determining its degradation rate. Our in vitro and in vivo testing results indicated that EPD demonstrated better corrosion resistance than MAO, implying the potential of electrochemical technology for surface modification of Mg or its alloys developed for orthopaedic applications.