Controllable degradation behavior, mechanical properties and biocompatibility of Mg-Sr-Mn alloys for the orthopedic medical applications

Orthopedic medical implants require matrix materials with moderate strength, low degradation rate and good biocompatibility. Magnesium (Mg) has emerged as a next-generation candidate for bone fixation; however, its rapid degradation leads to premature loss of mechanical integrity and implant-associated inflammation, limiting the clinical application of Mg alloys. In this study, we systematically investigated the mechanical properties, in vitro biodegradation behavior, biocompatibility and osteogenesis performance of newly developed novel extruded Mg-0.3Sr-xMn (SM alloy; x = 0, 0.4, 1.2, and 2.0 wt.%) alloys. Among them, the Mg-0.3Sr-0.4Mn alloy (SM04) demonstrated optimal comprehensive performance: its yield strength (205 MPa) and ultimate tensile strength (242 MPa) were 28% and 11.5% higher, respectively, compared to the Mg-0.3 Sr (SM0) alloy, while exhibiting a 54% reduction in corrosion rate (0.39 mm/year). Furthermore, the SM04 alloy maintained cell viability exceeding 90% and showed 2.46-fold higher alkaline phosphatase (ALP) activity than the SM0 alloy. However, excessive grain refinement, combined with weakened basal texture, may compromise corrosion resistance. Therefore, achieving an optimal composition and precisely engineering the microstructure are essential to balance mechanical properties, biodegradation rate, and biocompatibility. These findings suggest that Mg-Sr-Mn alloys hold great promise as advanced materials for orthopedic medical applications.