Changes in the microscopic spatial structure and mechanical properties of lumbar cancellous bone during OP progression and their correlation with macroscopic mechanical strength
Objective This study aims to explore the changing patterns and correlation of the microscopic spatial structure,micromechanical properties,and macromechanical properties of cancellous bone in the process of osteoporosis(OP)based on the os-teoporotic rabbit model.Methods 64 female white rabbits were selected and randomly divided into a sham operation group(Sham group,n=32)and an osteoporosis model group(OP group,n=32).White rabbits in the Sham and OP groups were randomized into 4 groups(n=8)at baseline(Pre-ovx),1,2,and 4 months,respective-ly.Bone mineral density(BMD)was measured by dual-energy X-ray absorptiometry(DXA)at 0,1,2,and 4 months after surgery.Lum-bar vertebrae specimens were collected and the micromechanical pa-rameters were measured by nanoindentation method,the microspatial structural parameters were measured by micro-computed tomography(Micro-CT),and the macromechanical strength parameters were mea-sured by axial compression test.Results With the extension of modeling time,BMD,maximum load(Lmax),elastic modulus of bone trabeculae,stiffness,hardness,trabecular thickness(Tb.Th)and trabecular number(Tb.N)gradually decreased,while the trabec-ular spacing(Tb.Sp.)gradually increased.Pearson's linear correlation analysis showed that Tb.Th had the strongest positive correla-tion with Lmax(r=0.926,P=0.000),modulus of elasticity(r=0.938,P=0.000),and hardness(r=0.921,P=0.000),all positively cor-related.Among the micromechanical properties,modulus of elasticity and Lmax(r=0.940,P=0.000)had the strongest positive correla-tion.Multiple linear regression showed that both Tb.Th(β=0.369,P=0.038)and elastic modulus(β=0.594,P=0.002)were positive-ly correlated with Lmax.Conclusion Tb.Th and the elastic modulus of the bone trabeculae are the factors that influence the macro-scopic mechanical strength of bone,and the elastic modulus has the most significant impact on the macroscopic mechanical strength of bone.So the elastic modulus can be used as a predictor of OP fracture.
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