The Development And Related Research Of Injectable Calcium Phosphate Cement/fibrin Glue/bone Morphogenic Protein Composites As Injectable Bone Graft Substitute

Objective The purpose of this study was to research one kind of injectable bone graft substitute with the advantages of good osteoinduction, shapement and biodegradability, by using injectable calcium phosphate bone cement (ICPC)/fibrin glue (FG) as the injectable carrier of bone morphogenetic protein (BMP). Methods Firstly, the injectable composites were compounded with ICPC and FG as volume ratio of 2:1. The crystallizing time and mechanical character of the compound material were measured and their constructions before and post burnt were observed by scanning electron microscope (SEM). Secondly, the composites of ICPC/FG/bBMP, ICPC/FG and bBMP were injected subcutanously or implanted into thigh muscle pouches of the mice randomly.To evaluate the effect of ectopic bone formation, Alkaline phosphatase (AKP), bone mineral density (DBM) and histology were observed at week 2 and 4 postimplantion. To compare the activity of bone formation, new bone was measured at week 4 postoperation. In the end, composites of ICPC/FG/BMP and ICPC/BMP were used to repair rabbit femoral condyle cyst bone defect. X-ray films, histological changes anddetection of new bone proportion and density were observed at different time after operation. The above parameters were used to compare the difference of degradation and bone repair capability of ICPC before and after FG was compounded. Result 1 .The average initial setting time (IT) of the compound material was 9.54 minutes and the average final setting time (FT) was 21.38minutes. The maximal anti-compression intensity was 30.82±1.77 Mpa and the terminal anti-extension intensity was 4.52±0.29 Mpa. By SEM, because FG distributed within the interspace of ICPC, the compound material had more compact structure compared with ICPC. Spaces between ICPC crystals were about 2-7nm with the porority 19.7%. After burnt, there were many large holes in ICPC with the diameter 10-18nm. The porority of CPC/FG composite was 32.6% and many extensive channels connected the holes of ICPC. 2. ICPC had no bone induction after compounded with FG Implants of ICPC/FG/bBMP composite induced new bone effectively. Grafts of bBMP stimulated litter osteogenesis while Implants of ICPC/FG showed no sign of new bone formation. The amount of induced new bone has significant difference statistically (p<0.05). 3. ICPC/FG/bBMP composite had obvious bone repair capability. By the end of week 16, new bone had bridged the gap between the proximal and distal fragments in ICPC/FG/bBMP composite. Histomorphologicaly, in ICPC/FG/bBMP composite, abundant of chondral and new bone islands were seen at the site of defects 4 weeks after operation, and a number of new bones formed and enlarged by both enchondral ossification and appositional formation at week 8. Remodeling of new bone and resorption were observed at week 16. New lamellar and woven bone...