CT Scan Based Finite Element Analysis Of Lumbar Vertebral Body

Osteoporosis is a very common disease and it can cause bone fracture of the elderly to be disabled.With the arrival of an aging society,it has increasingly been paying close attention. Especially the relationship between osteoporosis and other diseases of the elderly has become hotspot of medical research. It will provide a reliable scientific basis for the sick and elderly groups. In China, according to census results in 1990, the group that elder than 60 yesrs old accounted for 8.6% of the population, about 100 million people. To calculate a prevalence rate of 25%,the absolute number of elderly patients with osteoporosis at least 25 million people. Osteoporosis can be seen in China is not only a medical problem but also a serious social problem.Osteoporosis mainly occurred the region of rich in cancellous bone, such as the thoracolumbar spine, hip, and distal radius and the proximal humerus ankle. And the loss of human bone occurred in the vertebral firstly,so spinal bone's loss is a result of early detection and tracking of sensitive parts of the response to drug therapy.Lumbar is a major endure force,vertebral bone tender conditions and the intensity of their spinal vertebral is the two main factors in fractures research.In addition,the better knowledge about bone's quantity can estimate the position of fractures caused by osteoporosis.Therefore, the study will proceed with analysis of the two factors.By CT scans, to build three-dimensional finite element model, and analyse the forces'instance.Based on CT scans, which would result in vertebral cancellous bone tissue regional differences. Concrete steps are as follows:Firstly, to build a precise three-dimensional finite element model.1. Model's data acquisition Using CT scanning,can attain similar geometric entities,.CT raw data have been saved directly to the stability of a CD-ROM. Using the original image data to establish itself as a finite element model. We avoid repeatedoperation of the various factors contributing to the process of the subjective part of the data and information lost.CT scanning can provide an accurate cross-sectional geometry, digital express, a specimen of the advantages of easy.Moreover, the volume of data and any location can scan 3D image reconstruction, and image processing rapidly,obtain abundant raw data storaged, high-quality image reconstruction.2. RemodelingBased on the CT's data, we can using computer tomography technology and using Mimics and Ansys software.Three-dimensional reconstruction of five lumbar vertebrae L1~L5 (including upper and lower disc of each sections) in the three dimensional precision solid model.3. Vertebral cancellous bone with different elastic modulusBecause of this study was to use Mimics put vertebral material attributes in more detail given. 3D finite element analysis has provided a guarantee for the reliability of the results compared with the same kind of material which be given cancellous bone to same attributes.These results are more true and reliable.The second part is to study vertebral cancellous bone's material properties distribution.Each point's CT of L1~L5 vertebra shipped from Mimics10.01, the most appropriate CT experience formula that selected will change CT to the apparent density and elastic modulus. Each direction will be set aside three vertebral levels:superuior,middle,inferior.Each level is divided into five directions:anterior, posterior,left,right and center.Sowe we can gain 75 regions and calculated the average elastic modulus of each cube.Then we carry through statistical analysisto compare vertebral cancellous bone material attributes distribution.The study on material properties'distribution of vertebral cancellous bone shows:L1~L5 vertebra, differences between anterior of cancellous boneand other parts of cancellous bone's elastic modulus are marked, and modulus of elasticity of anterior is lower than the other position,that is to say, under the same force conditions,it will produce more stress, is prone to injury and occure osteoporosis.The result is corresponding to the clinical results that the anterior prone to osteoporosis.L1~L5 vertebra of the three-tier in five parts, the middle layer's location have significant difference and the difference is universal relatively.From an overall perspective, each vertebra's middle section modulus of elasticity is less than the superior and inferior section, the middle section of every vertebral body is risk.The third part is to determine load and gain maxium stress.Finite element model of load conditions is simulated a major human spinal load.After established material to L1~L5 vertebrae accurately,we choose four load conditions to compare the vertebral stress distribution and to discusse the results.Under different loads,the result of L1~L5 vertebra stress distribution showed:L5 lumbar vertebrae which is the greatest for the site, and the human body in normal walking and reverse movement of L5 force significantly larger than other segments of vertebrae. The day-to-day walk bearing is unavoidable,but reverse movement can be reduced. So elder persons should try to avoid reverse-tempered sport and choos bending category action.This will reduce the L5 vertebra injury probability.In this paper, a theoretical analysis of vertebral cancellous bone material properties and the distribution of the vertebral's stress under various load. These models have good mechanics and geometric similarity, the three-dimensional finite element modeling method is accurate and feasible. In addition,given the different elastic modulus to different element,these data can be reference to further lumbar 3D finite element analysis. In a certain extent,it is also a reference to the clinical diagnosis and prevention of osteoporosis.