Selection and preparation strategies of Mg-alloys and other biodegradable materials for orthopaedic applications: A review

Biodegradable materials and tissue engineering are gaining widespread attention because of their importance in bone fracture repair. Medically used implants made from these materials do not require secondary surgery to remove them. They also have the properties to stimulate bone growth and in situ degradation. Since biological and bio-corrosion properties in the physiological environment (PE) must also coincide with the mechanical properties during the healing process of bone, for this reason, it has become an exciting area of research. Because of the low tensile strength and hardness of biodegradable ceramics and polymers, they do not meet the mechanical requirements of the implant. In contrast, metals have much higher strength than bone, which causes a stress shielding effect. Therefore, alloying of biodegradable metals is needed to do. There is a need to create a proper strategy to enhance the material's properties to support the healing process of the fractured bone. After a detailed study of biodegradable materials, it was observed that Mg alloys possess good biocompatibility and mechanical strength. Therefore, further, this paper explored the methods by which biocompatibility of Mgalloys-based materials can be further improved and it was observed that they explicitly developed to ensure proper healing of the fractured bone. For this, the paper presents an overview of step-by-step strategies for manufacturing Mg-alloys for Orthopaedic applications. To ensure better biocompatibility with good mechanical strength, degradation behavior is explored. In last, it was found that alloys of Mg with Zn, Ca, Li, Zr, and Sr show a controlled degradation rate. Apart from selecting materials for making alloy, operations such as surface treatment, coating, polishing, also play a vital role in achieving a controlled corrosion rate with the good mechanical strength of Mg alloys.