In vivo study on the repairment of distal femur defects in rabbit with nano-pearl powder bone substitute.

Objectives: To evaluate the repairing ability of nano-pearl powder bone substitute in rabbit with defect of distal femur bone.

Methods: Thirty-two New Zealand rabbits were randomly divided into four groups: a nano-pearl powder/recombinant human bone morphogenetic protein 2 (rhBMP-2)/hyaluronic acid group, a nano-pearl powder/hyaluronic acid group, a nano-pearl powder group and a blank control group (=8 in each group). A defect with the diameter of 7 mm and height of 10 mm was prepared at the distal femoral metaphysis line of the rabbit.Different bone substitutes were planted, and the effect of repair was evaluated by macroscopic observation, imaging examination, and histopathological examination.

Results: The results of imageology showed that: the bone repairing effect in the nano-pearl powder/rhBMP-2/hyaluronic acid group was better than that in the pure pearl powder group and the nano-pearl powder/hyaluronic acid group, and which in the 3 experimental groups was better than that in the blank control group; The results of histology showed that: at the 4th, 8th and 12th weeks after the modeling operation, the speed of bone repair in the nano-pearl powder/rhBMP-2/hyaluronic acid group was faster than that in the pure pearl powder group and the nano-pearl powder/hyaluronic acid group, and which in the blank control group was far slower than that in the 3 experimental groups. The results of immunohistochemistry staining for osteocalcin antibody showed that: the osteogenic effect in the nano-pearl powder/rhBMP-2/hyaluronic acid group was better than that in the pure pearl powder group and the nano-pearl powder/hyaluronic acid group (both <0.05); there was no significant difference between the nano-pearl powder/hyaluronic acid group and the pure pearl powder group (>0.05); however, there was significant difference between the pure pearl powder group and the blank control group (<0.05). According to the staining results of Type I collagen antibody, there was no significant difference in the osteogenic effect between the nano-pearl powder/rhBMP-2/hyaluronic acid group and the nano-pearl powder/hyaluronic acid group (>0.05), but the osteogenic effect in the nano-pearl powder/hyaluronic acid group was better than that in the pure pearl powder group and the blank control group (both <0.05).

Conclusions: Nano-pearl powder and its bone substitute can promote the repair of bone defect, and the nano-pearl powder which contains rhBMP-2 has better osteogenic and repairing effect on defect.