Biochemical and biohumoral studies of bone regeneration and remodelling after implantation of magnesium pin

Magnesium degradable implants, notable for their mechanical and osteogenic properties, are ideal for temporary orthopedic applications but face limited clinical use due to inadequate follow-up methods for assessing implant osseointegration and tissue regeneration. This study assessed the potential of circulatory systemic biomarkers to monitor inflammation and bone regeneration following the bilateral implantation of Mg-alloys in rat’s femurs. Sixteen biomarkers of inflammation and bone regeneration were measured from plasma samples collected at multiple time-points up to 90 days after surgery. All animals (Mg-alloy group, Titanium group and SHAM -no-critical bone defect group) were monitored for pin placement and bone regeneration using computed tomography. Noteworthy findings included the higher concentration of OPG, DKK1, VEGF, and KIM-1 in SHAM group compared to implanted animals. The Mg-alloy group (WE43) showed lower concentrations of OPG and VEGF compared to titanium group on days 7 and 28. Histological analysis showed progressive bone regeneration around both types of implants, but WE43 degradation promoted a delayed regenerative process in respect to titanium. A notable finding was the low concentration of FGF23 and the high concentration of IL10 on day 28 in the WE43 group associated with a thicker intramedullary corrosion layer assessed through SEM/EDX analysis of bone-implant interface. Furthermore, the trace accumulation of WE43 degradation products (Y,REE) showed variable concentrations over time in the liver, spleen and kidney. This study provides valuable insights into the behavior of different implant materials in vivo, offering important implications on the safety of Mg-alloy implants and exploring the utility of systemic biomarkers as a follow-up technique.