The effect of medical biodegradable magnesium alloy in vivo degradation and bone response in a rat femur model with long-term fixation

Abstract

BACKGROUND: It is of great significance to understand the effect of the different corrosion behaviors of magnesium (Mg) alloys manufactured using different casting methods and implanted with different methods on the long-term implantation to expand the application of Mg-based biomedical implants. OBJECTIVE: The effects of four different casting and rolling speeds on the microstructure of an Mg–rare earth (Mg–Re) alloy were analyzed using electron backscatter diffraction (EBSD). METHOD: Four Mg alloys were obtained using vertical two-roll casting (TRC) at 10 m/min, 16 m/min, 24 m/min, and 30 m/min, and their microstructure, corrosion behavior and bone reaction in vivo were studied. RESULTS: The corrosion resistance of the alloy increases with an increase in casting speed and finer grain size of the cast-rolled parts. The Mg–Re alloys with TRC-10 m/min and TRC-30 m/min were selected for animal experiments. The two Mg alloys were made into metal rods and inserted into the rat femur to simulate the effect of Mg–Re on femoral healing under an injury condition. The rods were implanted for a long time to judge the effects of the Mg–Re alloy on the body. The TRC-30 m/min implants obtained highly mature new bone tissue in the case of bone injury. CONCLUSION: The in vivo experiments showed that the corrosion resistance of the TRC-30 m/min implant was better than that of the TRC-10 m/min implant. After 32 weeks of implantation, there were no pathological changes in the liver, heart, or kidney of rats in the TRC-30 m/min group, and the cell structure was normal.