Degradation of dicalcium phosphate dihydrate-coated Mg-Zn alloy and bone formation in vivo / 上海交通大学学报（医学版）

ABSTRACT

Objective To investigate the degradation of dicalcium phosphate dehydrate-coated Mg-Zn alloy in vivo and bone formation. Methods Left femoral condyles were drilled in 72 New Zealand rabbits, and were randomly divided into experiment group (n＝24, implanted with dicalcium phosphate dehydrate-coated Mg-Zn alloy rods), Mg-Zn alloy control group (n＝24, implanted with Mg-Zn alloy rods) and poly-L-lactide acid rod group (n＝24, implanted with poly-L-lactide acid rods). Serum concentrations of Mg~(2+) were examined 1 d pre-operation, and 1 d, 1 week, 2 weeks, 5 weeks and 10 weeks post-operation in experiment group and Mg-Zn alloy control group. Operation sites were examined by X-rays at 3, 6, 12 and 18 weeks post-operation. After X-ray examination at each time point, 6 rabbits in each group were sacrificed, and subjected to histopathological observation of live and kidney tissues by HE staining. Tissues from condyles of femur were observed by HE staining and 2, 4, 6-trinitrophenol rosein staining, and mineral apposition rate of bone was calculated. Results There was no significant difference in the concentrations of serum Mg~(2+) at each time point between Mg-Zn alloy control group and experiment group (P>0.05). X-ray examination revealed gas emerged near the implants 3 weeks after surgery in Mg-Zn alloy control group. However, there was no obvious histological abnormality in liver and kidney tissues. The mineral apposition rate was higher and the degradation of material was lower in experiment group than those in the other two groups. Conclusion Dicalcium phosphate dehydrate-coated Mg-Zn alloy has a favourable biocompatibility, and degrades more slowly in vivo.