Abstract: BACKGROUND: In recent years, platelet-rich plasma, concentrated growth factors, and 3D-printed nanoscale hydroxyapatite scaffolds have become popular research materials for bone transplantation. At present, the research directions of these materials are scattered, and there are few existing studies targeting large segments of bone and lack of comparison of different types of materials. Because the main component of long diaphysis is cortical bone, its healing is challenging.
OBJECTIVE: To evaluate and compare the effects of platelet-rich plasma, concentrated growth factor, and 3D micro-nanostructure composite scaffold on bone defect healing. 
METHODS: Thirty-two New Zealand white rabbits were enrolled to prepare radial bone defect model of 15 mm. According to the graft, they were divided into four groups (n=8): blank group (no treatment), platelet-rich plasma group (platelet-rich plasma), concentrated growth factor group (concentrated growth factor) and 3D composite scaffold group (3D micro-nanostructure composite scaffold). X-ray examination was performed at 1 day, 6 and 12 weeks postoperatively. Behavioral observation was performed at 12 weeks postoperatively. The rabbit ulnar and radial bone specimens were taken for Micro CT scanning to compare bone mineral density and bone volume fraction. Finally, the bone specimens were sliced and observed under a microscope. 
RESULTS AND CONCLUSION: (1) The platelet-rich plasma, concentrated growth factor, and 3D composite scaffold groups had different volumes of new bone with little behavioral difference, while the blank group had almost no new bone formation and obvious claudication occurred at 12 weeks after operation. (2) X-ray imaging was better in each intervention group than that in the blank group at 6 and 12 weeks after surgery. The difference in gray values was obvious between the intervention groups, but there was no significant difference between platelet-rich plasma and concentrated growth factor groups at 12 weeks. (3) At 12 weeks after surgery, there was no statistically significant difference in bone mineral density and bone mass between the platelet-rich plasma and concentrated growth factor groups, but all parameters were better than those in the 3D composite scaffold group. (4) It is concluded that undoubtedly platelet-rich plasma and concentrated growth factor can promote the early formation of new bone, but there is no significant difference in the long-term effects of platelet-rich plasma and concentrated growth factor. The inorganic scaffold made of hydroxyapatite is difficult to promote the healing of bone defects completely, and other organic components must be added to improve its performance to maximize the osteogenic effect.

Key words: bone defect, platelet-rich plasma, concentration growth factor, hydroxyapatite, composite scaffold, radius, bone healing