Mg-based bone implants show promising osteoinductivity and controllable degradation: A long-term study in a goat femoral condyle fracture model

In this work, the in vivo biocompatibility and biodegradation behavior of Mg-Nd-Zn-Zr alloy (denoted as JDBM) screws were studied using a goat femoral condyle fracture model. Blood analysis indicates that the liver and kidney functions of goats were not affected by JDBM, JDBM coated with brushite (denoted as JDBM-DCPD) and PLA implants. Radiographic analysis shows that JDBM-DCPD screw has lower degradation rate than JDBM. Histological images show that compared with PLA, JDBM and JDBM-DCPD show superior effect to promote more new bone formation. JDBM-DCPD group has more new bone formation than JDBM group, indicating good osteoinductivity of DCPD coating. JDBM group show higher osteogenic factors level (BMP2, ALP and OC) in peri-implant callus tissue than PLA group. Long-term (18 months) in vivo implants Micro-CT result shows that the degradation of JDBM-DCPD screw may be slower than desirable, and the thickness of DCPD coating could be further adjusted to match the degradation to the bone recovery.