Development of a modified-in vitro corrosion fatigue test rig for biodegradable load-bearing metallic implants

Abstract

Corrosion fatigue is a major factor leading to sudden failures in load-bearing orthopaedic implants, particularly in biodegradable ones that corrode more quickly than permanent implants. In the current study, we developed a novel modified-in vitro corrosion fatigue (MICorF) rig that incorporates several key parameters—such as loading mode, blood buffering capacity, gradual bone healing processes, and the synchronization of corrosion and cyclic damage—aimed at closely mimicking in vivo conditions. The functionality of the MICorF was tested with an experimental extruded ZX00 (Mg-0.5Zn-0.5Ca) Mg alloy. The results showed that the ZX00 Mg alloy possesses a limited biomechanical performance. Based on the SEM micrographs, the presence of intermetallic particles in the alloy microstructure and the subsequent galvanic corrosion phenomena could be taken as the main cause of failure. According to the results yielded by the MICorF, the ZX00 alloy withstands at least 20 days under the studied physiological conditions and polarization corresponding to the pitting conditions.