Experimental Study On Reparing Rabbit Radius Defect Using Compoud Of Calcium Phosphate Cement With Micromorselized Bone

Objective To explore the optimum mixing ratio of calcium phosphate cement(CPC) with micromorselized bone for reparing rabbit's radius defect by the experiment in vitro and vivo.Study in vitroMethods Bilateral femur of six Japanese macro-ears rabbits were made into morselized bone. There were two groups, experimental group and control group. In experimental group, the materials were used as the ratios of morselized bone to CPC with 1 to 1,1 to 2,1 to 3,1 to 4 and 1 to 5; in control group CPC was used after it was set. The maximum compression strength and setting time of the materials in experimental and control group were tested. The cell multiplication was evaluated by MTT after mesenchymal stem ells were cultivated in leaching liquor of materials. The number and morphous of cells were observed by electron microscope.Results The cell multiplication in materials mixed with ratios of 1 to 2 and 1 to 3 was better than those in the materials mixed with other ratios by MTT, It indicated that there was a significant difference (P<0.05). The cells grew well on the surface of the materials mixed with proportions of 1 to 2 and 1 to 3, and the number of cell on the surface of other materials was smaller than that of cell on the surface of the above two materials. The maximum compression strength and setting time of the material mixed with a ratio of 1 to 3 was moderate, and there was a significant difference between CPC and material mixed with a ratio of 1 to 3(P<0.05).Conclusions The ratio of 1 to 3 was thought to be optimum one in manipuility, biomechanics and cell compatibility.Study in vivoMethods The animal models of bilateral radius defect were created by surgery on Japan white big ear rabbits. The compound with a ratio of 3 to 1 in a leg were implanted in experimental group, and calcium phosphate cement were used in the contrasting group. Then x-ray, bone density, maximum torsional moment and histology inspection were made at different time, and osteogenesis and degradation of the materials of the two groups were analyzed.Results Enhancement of osteogenesis was found in the experimental group, and the materials were enclosed significantly by bony callus at the 8th week; the defects were repaired and the materials were degraded completely at the 16th week. The numbers of bone mineral content in the experimental group were more than those in the control group (P<0.01). The maximum torsional moment was (0.843±0.016) mN in the experimental group and (0.540±0.029) mN in the control group (P<0.01). It was also obseved by histology that the number of newly formed bone of the experimental group were more than those of the control group, and the degradation rate of materials in the experimental group was faster than that in the control group at the same time.Conclusion The compound of calcium phosphate cement with morselized bone by a ratio of 3 to 1 significantly improved the defect reparing and materials degradation...