Resorbable metallic implant of magnesium and its alloys had been studied since the 1900s.
However, the excessive gas production resulted in its unpopularity after CoCr alloys and stainless
steel were developed. With the advancement of alloying technologies, its use as a resorbable implant
has re-emerged recently. Foreign researchers focused on the use of AZ-series and magnesium-rare
earth metal alloys. However, the corrosion property of AZ-series alloys is unsatisfactory, and the
effect of rare-earth metals on human is poorly studied. Therefore, we have investigated on the
feasibility of using commercially available AM-series magnesium alloys. Previous researchers
avoided this alloy series presumably because of the potential health effect of manganese, however our
toxicological risk assessment revealed that the exposure level would be lower than the NOAEL (No
Observable Adverse Effect Level), thus it is unlikely to cause any observable health effect on healthy
individuals. Subcutaneous implantation of AM-series magnesium alloys into a mouse model for six
months confirmed that, while all alloys tested showed slow corrosion and no observable in vivo
toxicity, pitting corrosion did not occur for AM-series alloys but was frequent for AZ91D. This
suggests that AM-series magnesium alloys are good candidates of resorbable metallic implants.
Stacking-fault mediated plasticity and strengthening in lean, rare-earth free magnesium alloys
