Comparison of modified injection molding and conventional machining in biodegradable behavior of perforated cannulated magnesium hip stents

In this study, perforated cannulated magnesium (Mg) hip stents were fabricated via modified Mg injection molding and conventional machining, respectively. Additionally, the stent canal was filled with paraffin to simulate injection of biomaterials. The microstructure, mechanical performance, corrosion behavior, and biocompatibility were comparably studied. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) showed higher affinity of interstitial element such as oxygen and carbon as consequences of routine molding process. After immersion in SBF, machining stents showed reduced degradation rate and increased deposition of calcium phosphate compared to molding stents. Corrosion resistance was improved via paraffin-filling. Consistently, the hemolysis and in vitro osteoblast cell culture models showed favourable biocompatibility in machining stents compared to molding ones, which was improved by paraffin-filling treatment as well. These results implied that the feasibility of the prepared machining stents as the potential in vivo orthopaedic application where slower degradation is required, which could be enhanced by designing canal-filling injection of biomaterials as well.