Biomechanical Analysis Of Lumbar Cortical Bone In The Elderly People

Objective: Using CT scan and finite element technology,the L1-S1 lumbar model was established to measure the mechanical characteristics of the lumbar cortical bone and the stress data of the cortical bone screw trajectory of the elderly group,to verify the etiology of the elderly osteoporotic vertebral compression fracture and the cortical bone trajectory screw technology.Methods: Using Mimics15.0,Geomagic Studio 12.0,Pro / E 5.0,hypermesh12.0 and Abaqus2016 an elderly woman's lumbar three-dimensional finite element model was established,then the following step was implemented: 1.applying a vertical load(600N)from the upper endplate of L1,after setting constraints on sacroiliac joint,measuring date from all 6 vertebral bodies in the standing position and other four positions(anterior flexion,posterior extension,lateral flexion,The maximum stress at the rotation);2.Under the same load we also measured the stress of the cortical bone screw trajectory areas in different positions(anterior flexion,posterior extension,lateral flexion,rotation).Results: 1.Under the same load,the range of motion of the disc are close to the mechanical results and the model bio-fidelity were good enough;2.Maximum stress of each vertebral in standing position is relatively small compared with other four positions.The maximum stress of the L1 cortical bone was 27.49Mpa(posterior extension position).In L2 was13.31Mpa(lateral flexion),and L3 was 13.7Mpa(anterior flexion),and the maximum stress of cortical bone of L4 ?L5 vertebral body appeared in the extension and lateral Flexion;3.The results of the cortical bone point in all position shows the stress on the medial point of pedicle on both sides was the largest.Conclusion: 1.The stress of the cortical bone of the vertebral body in the flexion,extension,lateral flexion and rotation position was significantly increased compared with vertical position.Avoiding those positions can reduce the stress on vertebral body and preventing fractures.2.The maximum stress point of each vertebral body was not in the area of the cortical bone screw trajectory,the medial cortical bone of pedicle was most stressed and injuries should be avoided during surgery...