| Background and PurposeThe repair of long bone segment defect is one of the difficult problems in orthopedic clinic. Both transplantation of allochthonous bone or autogenous bone and the bone lengthening operative, all have a lot of limitations.Nowadays, tissue engineered bone to repairing bone defect have become the hot topical spot in this researching area. Its ability of?osteogenesis, osteoinduction , strengthing support, materials ratio degradation, vascular reconstruction, and so on, all these have make great development, but have not made any substantial progresses. The development of microsurgical technique injects fresh energy to the development of the bone defect ?therapy. But to the big segment bone damage, still have a lot of deficiency. In this experiment, we design artificial bone materials united autogenous bone with blood for transplantation to repair sheep big segment bone damage. The purpose is to investigate the osteogenous ability of the tissue engineered bone with autogenous bone and the feasibility of this surgical operative way.Experimental Design and MethodTwenty-one Mongolia sheep were allocated into 4 groups, experimental group(n=6),material control group(n=6), ulna control group(n=6), Blank control group(n=3).To operate and result in 40mm segmental bone defects in the radius and ulna of sheep. To transplant vascular autogenous bone with artificial bone into sheep radius defects of experimental group. Only materials was implanted into materials control group. Only ulna with atery was transplanted into ulna control group. Blank control group was completely unoccupied. After the operation, at 4th, 12th and 24th weeks time-point, X-ray were brought into respectively. Groups of sheep were sacrificed and specimens were procured at 24th weeks after surgery, takeing gross observation, CT scanning and three Uygur reconstruction and decalcificated histological sections as the observed indices. Based on observed indicators of bone defects in each group, the repairing ability were compared.Experimental ResultRadiological Observation: After the operation, at 12w time-point, the X-ray photos showed: callus were seen forming at the bone defects in experimental group, materials control group and ulna control group. The defects of experimental group were backfilled by callus completely, their central area showed a fuzzy outline of the marrow cavity. After the operation, at 24w time-point, bone fusion appeared at the edge of fracture in three groups? by X—ray film and the specimen CT scanning. The bone defects were repaired completely in experimental group and its bone mineral density was near to the normal bone; and showed the clear outline between the cortical and marrow?bone. The bone defects were not repaired completely in materials control group and ulna control group. In blank control group, at 12w time-point, bone marrow cavity closed, and callus formation was not seen in the place of bone defect.Histological Observation: On 24w time-point, past operation, there were much compact bone in the outer layers of radius in experimental group, materials control group and ulna control group. In the experimental group, a large number of bony trabecular and myeloid tissue formed at the central place of bone defect, the material of artificial bone was not found. In the materials control group, the few artificial materials remained and premature myeloid tissue were found. In the ulna control group, the bony cortex were slightly thicker, but the central medulla cavity were not broadens obviously. Their defect areas filled with fibro scar tissues in blank control group.Demographic AnalysesThe differences were significant among each group.ConclusionThe quantity and quality of new bone formation in the experimental group was higher and faster than those in materials control group and ulna control group. The osteogenous ability of tissue engineered bone in experimental group was strongest and its degradation ratio was the highest. The result showed that the experimental design of the bioactive artificial bone united vascular autogeneous bone transplanted is relatively rational and could accelerate the repairing of segment at defect of long bone. The composite materials of PLGA-TCP/BMP-2 is an ideal artificial bone materials. |
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