In vivo evaluation of bioabsorbable Fe‐35Mn‐1Ag: first reports on in vivo hydrogen gas evolution in Fe‐based implants

This work investigates the influence of Ag (1 wt%) on the mechanical properties, in vitro and in vivo corrosion, and biocompatibility of Fe‐35Mn. The microstructure of Fe‐35Mn‐1Ag possesses a uniform dispersion of discrete silver particles. Slight improvements in compressive properties are attributed to enhanced density and low porosity volume. Fe‐35Mn‐1Ag exhibits good in vitro and in vivo corrosion rate of Fe‐35Mn due to an increase in microgalvanic corrosion. Gas pockets, which originate from an inflammatory response to the implants, are observed in the rats after 4 weeks implantation but are undetectable after 12 weeks. No chronic toxicity is observed with the Fe‐35Mn‐1Ag, suggesting acceptable in vivo biocompatibility. The high corrosion rate of the alloy triggers an increased level of nonadverse tissue inflammatory responses 4 weeks after implantation, which subsequently subsides at 12 weeks. The Fe‐35Mn‐1Ag displays properties that are suitable for orthopedic applications