Recent progress in Mg-based alloys as a novel bioabsorbable biomaterials for orthopedic applications

Traditional orthopedic metal implants, such as titanium (Ti), Ti alloys, and cobalt-chromium (Co-Cr) alloys, cannot be degraded in vivo. Fracture patients is must always suffer a second operation to remove the implants. Moreover, stress shielding, or stress protection occurs when traditional orthopedic metal implants are applied in fractures surgery. The mechanical shunt produced by traditional orthopedic metal implants can cause bone loss over time, resulting in decreased bone strength and delayed fracture healing. Biodegradable metals that ‘biocorrode’ are currently attracting significant interest in the orthopedics field due to their suitability as temporary implants. As one of the biodegradable metals, magnesium (Mg) and Mg alloys have gained interest in the field of medicine due to their low density, excellent biocompatibility, high bioresorbability, and proper mechanical properties. Additionally, Mg ions released from the metal implants can promote osteogenesis and angiogenesis during the degradation process in vivo, which is substantially better for orthopedic fixation than other bioinert metal materials. Therefore, this review focuses on the properties, fabrication, biological functions, and surface modification of Mg-based alloys as novel bioabsorbable biomaterials for orthopedic applications.