Review on magnesium and magnesium-based alloys as biomaterials for bone immobilization

Magnesium alloy has become one of the third-generation biomedical materials to promote bone tissue regeneration. Compared to other metal implants, magnesium metal is biodegradable and continues to degrade as the bone tissue heals, eliminating the need for secondary surgical removal. The Young's modulus of magnesium alloys is closer to human bone, and the magnesium ions produced by degradation are osteoinductive and antimicrobial, which can stimulate new bone formation, diminish stress shielding effects and reduce the risk of implant failure due to infection. However, the rapid corrosion rate of pure magnesium in a physiological environment can result in the mechanical integrity of the implant being compromised before the bone tissue has fully healed and the requirements associated with bone implantation cannot be met. In order to reduce the degradation rate of magnesium implants, the mechanical properties and corrosion properties of magnesium-based implants can be improved through machining, alloying and topology optimization to match the degradation rate of magnesium-based implants with the healing rate of bone tissue. As a bone implant fixation material, the mechanical properties, corrosion performance and biocompatibility of magnesium alloys are crucial. This work reviews studies related to the organization, mechanics, biocompatibility and corrosion properties of different magnesium-based alloys and analyzes the effect of different manufacturing processes on the mechanical properties of magnesium alloy implants. In addition, this paper also investigated the corrosion and wear behavior of magnesium alloy implants after implantation and analyzed the effect of different factors such as pH, temperature and stress on the corrosion behavior of magnesium alloy. Finally, in order to improve the implantation success rate of magnesium implants, the effects of different coatings on the biocompatibility and corrosion properties of magnesium implants are discussed.