Advancements in biodegradable magnesium matrix composites for orthopedic implant application: Mechanical, corrosion and biocompatibility perspectives

Metal orthopedic implants made of stainless steel, cobalt-chromium (Co-Cr), and titanium alloys are widely used nowadays. These materials produce poisonous ions and a stress-shield effect in the body. The implant then often needs to be removed by subsequent surgery. Magnesium (Mg) and its alloys have emerged as a viable solution to these issues. However, the deterioration rate of Mg is very fast, leading to unanticipated degradation and premature implant failure. The therapeutic applications of these implants are constrained by heterogeneous corrosion, causing rapid loss of mechanical characteristics. To increase elastic modulus and retain ductility without significantly increasing weight, reinforcements can be incorporated into the Mg matrix to develop Mg composites. Various engineering techniques, like adding reinforcement, treating the surface, and altering the synthesis methods, enhance the mechanical and biocompatibility properties of magnesium composites. In this context, this review article focuses on the different mechanical properties, strengthening mechanisms, corrosion characteristics, and biocompatibility of different Mg-composites. To increase the use of degradable Mg-based composites, current achievements in this sector are highlighted, which would help to choose potential topics for future research.