Nano Indentation Technique Was Use To Explore The Experimental Study On The Change Of Micromechanical Properties Of Bone

Objective: to understand the changes of the mechanical characteristics of bone microstructure in osteoporosis by using nanometer indentation technique,and to explore the mechanism of its occurrence and provide theoretical basis for the diagnosis and treatment of osteoporosis.Methods: 1.Preoperative lumbar vertebral density examination was conducted for patients undergoing clinical ascending lumbar vertebral augmentation and decompression surgery to distinguish between osteoporosis and non-osteoporosis patients.2.The 4th lumbar vertebral(L4)laminar bone of20 patients with osteoporosis were collected as the experimental group.The 4th lumbar spine(L4)laminar bone of 20 non-osteoporosis patients were used as the control group.3.Micro-CT on two groups of L4 vertebral plate Bone scan,Evaluation V6.5-3 software for quantitative analysis and comparison of two groups of L4 vertebral Bone plate relative Volume of Bone or Bone Volume fraction(Proportion or Percentage of the Volume of Interest of ipads,BV/TV),trabecular Bone isolation(trabecular Separation/apacing,Tb.Sp,TrabecularThickness(Tb.Th),Structure Model index(SMI).4.The two groups of L4 vertebral plate bone were sliced and polished,made from 3 mm thick,smooth on both sides of the sample,on the nano indentation test,each test sample 10 points,calculate the hardness and elastic modulus.Results: 1.There was no significant difference in gender,age,BMI and other general data between the two groups(P>0.05).2.By dual-energy X-ray scanning,the bone density of the experimental group was significantly lower than that of the control group(P<0.05).3.The results of MicroCT scan showed that the trabecular bone marrow in the experimental group was thin,intermittent and disordered.By the Evaluation V6.5-3 software analysis,the experimental group the bone volume fraction(BV/TV),bone trabecular thickness(Tb.Th)than the control group significantly decreased(P < 0.05),and trabecular bone separating degree index(Tb.Sp),the structure model(SMI)higher than control group obviously(P < 0.05).4.Nano indentation test results showed that the hardness and elastic modulus of trabecular bone in the experimental group were significantly lower than those in the control group(P<0.05).Conclusion: 1.Nano indentation technology has the advantages of high high displacement high score,ultra-low load and undamaged samples,which can be used for mechanical testing of bone microstructure.2.The fracture of bone microstructure and the decrease of elastic modulus of bone microstructure in osteoporosis patients are the main causes of bone strength decline.