[Study on the bone regeneration induced by advanced-platelet-rich fibrin and β- tricalcium phosphate composite]

To explore the osteogenesis effect of advanced-platelet-rich fibrin (A-PRF) and β-tricalcium phosphate (β-TCP) composite.

Thirty-two healthy female New Zealand rabbits were randomly selected. A-PRF was prepared by collecting blood from middle auricular artery. Rabbits were randomly divided into 6 groups: groups A, B, C, D, and E (6 rabbits in each group) and group F (2 rabbits). Bone defects (6 mm in diameter, 8 mm in depth) were drilled into femur condyle of each rabbit's both back legs. Then A-PRF and β-TCP composites manufactured by different proportion were planted into bone defects of group A (1∶1), group B (2∶1), group C (4∶1), group D (1∶2) and group E (1∶4) ( V/ V). The bone defect was not repaired in group F. The specimens were collected at 8 and at 12 weeks after operation. Then gross observation, X-ray examination, Micro-CT examination, and biomechanical test were performed. The bone volume/total volume (BV/TV), trabecular number (Tb.N), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp), compressive strength, and modulus of elasticity were calculated.

The gross observation and X-ray examination showed that the osteogenesis effect at 12 weeks was better than that at 8 weeks. At the same time point, the repair of bone defect and the formation of new bone in group B were better than those in other groups. Micro-CT examination showed that the trabeculae of new bone in group B were the most and the trabeculae arranged closely at 8 and 12 weeks. Besides there were significant differences in BV/TV, Tb.N, and Tb.Sp between group B and the other groups ( P<0.05). There were significant differences in Tb.N and Tb.Th in group B, BV/TV and Tb.Sp in group C, Tb.Sp in group D between 8 weeks and 12 weeks ( P<0.05). Biomechanical tests showed that the compression strength and elastic modulus of group B were the highest, and the compression strength and elastic modulus of group C were the lowest at 8 and at 12 weeks, showing significant differences ( P<0.05). There were significant differences in compression strength and elastic modulus of each group between 8 weeks and 12 weeks ( P<0.05).

The A-PRF and β-TCP composite can repair femoral condylar defects in rabbits, and the osteogenesis is better in proportion of 2∶1.