Biomechanical Experimental Study On The Effects Of High-G Mechanical Environment On Bone

Purpose:This subject studies animal effects to study the effects of high-G extreme environments on bones.A high G mechanical load was applied to rats,and the damage of high G mechanical environment to bone tissue was observed from two aspects: morphological structure and mechanical properties.The influence of high G mechanical environment on bone was discussed.To lay a theoretical foundation for combating high-G extreme mechanical environment and preventing bone-related injuries.Method:A total of 120 male Wistar rats were randomly divided into 3 groups: 2 groups,4 weeks group,and 6 weeks group,with 40 rats in each group.Each group was randomly divided into5 groups: control group,2G group,4G group,6G group and 8G group,with 8 animals in each group.Rats in the high G group were exposed to high G load 3 times a day,each lasting for 3 minutes,with an interval of 40 minutes,5 days a week.The control group was raised normally.At the end of the experiment,bilateral femurs of rats were obtained and tested for macromechanical properties based on three-point bending,microscopic microstructure parameters based on Micro-CT,and micromechanical properties based on nanoindentations.Result:In terms of macroscopic mechanical properties: The high-G mechanical environment can reduce the macroscopic mechanical properties of the bone in the two dimensions of G value and loading time,mainly in reducing the ultimate load and ultimate deflection of the femur.In terms of mesoscopic microstructure,the high-G mechanical environment can 3damage the microstructure of cortical bone and cancellous bone in the two dimensions of G value and loading time,mainly in increasing the cortical bone porosity(Po)and small bone Beam resolution(Tb.Sp),reduced cortical bone mineral density(BMDc),bone volume fraction of bone(BV/TV),trabecular bone thickness(Tb.Th),number of trabecular bone(Tb.N).In terms of micromechanical properties: under 2G load,the ratio of femoral elastic modulus to elastic modulus hardness increases,suggesting that the femoral micromechanical properties may be enhanced.But with the increase of G value,it can reduce the microscopic mechanical properties of bone,mainly in reducing the elastic modulus of the femur and the elastic modulus hardness ratio.Conclusion:The high-G mechanical environment can destroy the macroscopic mechanical properties,mesoscopic microstructure and microscopic mechanical properties of bones in two dimensions of G value and loading time.However,under 2G load,the ratio of femoral elastic modulus to elastic modulus hardness increases,suggesting that the 2G environment may enhance the femoral micromechanical properties.