|
The purpose of bone defect repair is common in orthopedic clinical problems, a long time, people looking for a good artificial alternative materials used to repair bone defects, but the result is not satisfactory. Prepared in this experiment demineralized bone matrix particles (DBM) / calcium phosphate cement (CPC) / recombinant human bone morphogenetic protein -2 (rhBMP-2) composites, explore the mechanical properties, structural characteristics and biocompatibility identify the best formulation of the composite material. Further observation the composite implant bone defects ultrastructure, X-ray and histological characteristics, evaluation of the material to repair large section of long bone defects and degradation of performance, to provide the basis for clinical application and mass production. Methods: (1) pre-rabbit DBM adsorption method in the rhBMP-2 DBM composite press dBm: the quality of the composite material than for that 0.1,0.2,0.3,0.4,0.5,0.6,0.7 is recipe with CPC composite preparing a composite material containing rhBMP-2 was about 1.2 × 106 mg / m3. (2) DBM quality ratio is 0.1, 0.2, 0.3, 0.4 composite line in vitro determination of compressive strength and scanning electron microscopy (SEM) observations, to investigate the mechanical properties, structural features, to find the best formulation of the composite material . (3) by the toxicity experiments, the coagulation test, hemolysis test, pyrogen experiments and muscle implantation Experimental Evaluation of biocompatibility of the material. (4) the the DBM mass ratio of 0.2 columnar composite bone implanted in rabbit femoral condyle 0.5cm defect, 6, 12, and 24 weeks after surgery were sacrificed for histological and scanning electron microscope, the evaluation of its performance. (5) mass ratio of 0.2 and 0.3 columnar composite implanted rabbit 1.5cm long radial bone defects and femoral condyle defects, 6,12,24,36 week after watching the X-ray findings, histological morphology and ultrastructure to evaluate its ability to repair large section of long bone defects and degradation of performance. Results: (1) DBM mass ratio within the range of 0.2 to 0.4, the composite material more irregular fracture of more than 100μm. The DBM mass ratio ≤ 0.1, most of the material within the gap lt; 100μm. DBM mass ratio ≥ 0.5 also look when DBM and CPC loss of binding and plastic. With a the DBM mass ratio increases, the the material ultimate compressive strength decrement, the mass ratio of the ultimate compressive strength of 0.1, 0.2, 0.3, 0.4 (8.12 ± 0.79) MPa (5.46 ± 1.13) MPa (5.13 ± 1.18) MPa (1.49 ± 0.61) MPa. Each set of data by analysis of variance, a statistically significant difference (P lt; 0.05), the mass ratio of 0.2, 0.3 with no statistically significant difference (P GT; 0.05) and (1.49 ± 0.61) MPa less than human cancellous The average compressive strength of the bone. (2) composite has good biocompatibility. (3) histological and scanning electron microscopy, see: composite implanted in the femoral condyle defect after the sixth week of composite materials - bone interface vague, issued by the places bone continuous fibers through the interface, woven bone-like structure began to inside the material ingrowth. Week 12 vessels and osteoblasts are formed within the composite. Week 24 bone defect repair bony connection, most of the material replaced by new bone. (4) The composite implant rabbit 1.5cm long radial defects, X-ray showed: the sixth week of composite materials - bone interface fuzzy around the callus regeneration. 12 weeks callus rich materials - bone interface disappears, the material is degraded lose their shape. Week 24 material is degraded more obvious, the medullary cavity recanalization. Week 36 material replaced by new bone marrow cavity recanalization. Histological examination also supports this result. Composites were implanted in the femoral condyle defect, X-ray showed: 6 weeks to 24 weeks, the material is gradually degraded, the density decreased. Scanning electron microscopy results also reached the same conclusion. Conclusion: With the the DBM mass ratio increases, the pores are more rich and gradually reduce the mechanical strength of materials. The DBM mass ratio of 0.2 to 0.3 the composite material can be used to repair a low load-bearing parts of the cancellous bone of the bone defect. The composite material has good biocompatibility, implant bone defects can promote cells, blood vessels, bone ingrowth, readily biodegradable and autologous bone substitute can be used to repair large bone defects.
|