Mesoscopic Biomechanical Modeling Analysis And Dynamic Impact Study Of Rabbit Vertebrae

The spine is the central pillar of the human body and has the functions of supporting the trunk and protecting the spinal cord.However,with the rapid development of industrialization,spine injuries caused by traffic accidents and high-altitude falls account for more than 50%,and thoracolumbar spine injuries can account for 80%.If a spinal cord injury occurs further,the patient may be at risk of paralysis,placing a heavy burden on the family and society.Therefore,to explore the mechanical characteristics of the spine when subjected to impact loads,provide biomechanical guidance for the clinical treatment and rehabilitation of spine injuries.Considering the complexity of the structure and function of the spine,this article mainly takes the single vertebral body of the New Zealand white rabbit spine as the research object,adopts the experimental measurement and finite element simulation method,through the dynamic impact test of the single vertebra of the rabbit,Static compression test and finite element analysis to explore the structural and biomechanical damage characteristics of the entire vertebra and local cancellous bone.The specific research content is as follows:(1)Use a self-made impact test stand to perform a dynamic impact test on a single vertebra of the rabbit spine,use a digital storage oscilloscope to record the signal of the dynamic impact force sensor,obtain the impact load-time curve,and compare it with the compression failure load of the single vertebra;(2)Record the dynamic impact process of the rabbit vertebral body with a high-speed camera,convert the video of the vertebral destruction process into a picture,and analyze the strain of the vertebrae with Match ID software;(3)Take out the cancellous bone specimens at different positions in the vertebrae with a hand electric drill,and perform the static compression experiment on the cancellous bone specimens on the Instron 3343 universal material testing machine to obtain the load-displacement curve and stress-strain curve,and obtain the apparent Parameters of density and elastic modulus;(4)Micro-CT scan of a single vertebra of the rabbit spine to obtain a clear image of the vertebrae,establish a finite element model of cancellous bone through medical image processing software(Simpleware,3-matic and Hyper Mesh),and use finite element analysis software(Abaqus)Simulation and analysis.Through the processing of experimental data and analysis of finite element simulation,the following conclusions can be drawn:(1)The dynamic impact test of single vertebrae shows that for the thoracic and lumbar vertebrae of the rabbit spine,the static compression load value is less than the dynamic impact load value;the dynamic load coefficient of the thoracic spine is greater than that of the lumbar spine;whether it is static compression or dynamic impact The equivalent stresses of the thoracic and lumbar vertebrae showed a similar trend of increasing first and then decreasing,and mutations occurred in the thoracolumbar vertebrae and stabilized at the lumbar vertebrae;the energy curve of the vertebrae increased from slow to fast,corresponding to the difference of the vertebrae Destruction phase,and energy rebound occurs;(2)The processing and analysis of the image of the impact process through Match ID software show that the longitudinal strain of the vertebral body when it is subjected to axial impact is much greater than the lateral strain,so it is necessary to strengthen the protection of the spine in the axial direction to avoid excessive axial load;(3)The static compression test of cancellous bone shows that the cancellous bone has a lower failure load and weaker bearing capacity,and the failure process is only one stage,similar to that of other porous homogeneous materials;the cancellous bone is obtained by calculation Apparent density and elastic modulus parameters are prepared for the material properties of the mesomodel finite element analysis;the increase in the bearing capacity of the cancellous bone is due to the trabecular bone filling the cavity and being gradually compacted,the bearing capacity reaches the limit The posterior trabecular bone collapses and the material is destroyed;(4)The finite element analysis shows that the stress distribution of the cancellous bone of the vertebral body is not uniform when the compression load is applied,the stress value of the thinner trabecular bone reaches the maximum value first,and the cancellous bone will be sparse to the bone density The side of the incline is inclined,and the rod-shaped trabecular bone is destroyed first.The parameters of stress and strain of normal cancellous bone and osteoporotic cancellous bone are quite different.After osteoporosis,its mechanical properties are reduced a lot,so we should pay attention to avoid the occurrence of osteoporosis;(5)Through the experiment and finite element comparative analysis of vertebral cancellous bone,the growth trend of the curve in the online elastic phase is basically consistent,which verifies the effectiveness of the model;(6)The mesoscopic modeling and analysis of the vertebral body has important research significance and value for the study of the macroscopic structure and characteristics of the vertebral body,and it can find its meso or microscopic mechanism or cause for the performance of the macroscopic characteristics.The parameters obtained by the research results in this paper are of great help to improve the accuracy of finite element simulation,and can provide guidance for the diagnosis and rehabilitation of spinal injury,and also have a reference for the protection and protection of clinical medical spine.