Investigation into Etiology of Idiopathic Scoliosis

由于特发性脊柱侧凸的出现以脊柱变形为特征，因此对力学方面的病因学研究有助于为研究生理原因和开发合适的治疗方法奠定基础。本研究的目的是明确特发性胸椎侧弯的力学病因，重点研究Shinoda等人和Dickson等人提出的椎体与周围结构生长速度不平衡所产生的屈曲机制的假说。结果产生了减少胸椎后凸的畸形，类似于在青春期早期观察到的健康儿童的情况。在增大变形的过程中，得到了对应于冠面第一弯曲模式、第一旋转模式、矢状面第一弯曲模式和冠面第二弯曲模式的第一至第四屈曲模式。第四模式的形态与临床形态吻合较好。考虑到体位对控制这些第一弯曲和旋转模式的产生的影响，以及缺少主要肌肉来矫正第二弯曲模式，我们提出了一个假设，即在胸椎特发性脊柱侧弯的机制中，冠状面第二弯曲模式是最有可能的病因之一。为了更准确地估计第四阶屈曲模式的增长速度和形状，尝试采用更精细的有限元模型进行非线性分析，并用力学模型进行实验。在研究项目方面，制作了有限元模型，并进行了初步试验。在今后的工作中将会取得足够的成果。

Since the appearance of idiopathic scoliosis is characterized by deformation of the spine, etiological research into mechanical aspects can help to establish the foundations for investigation of physiological causes and development of suitable treatments. The objective of this study was to make clear the mechanical etiology of thoracic idiopathic scoliosis, focusing on the hypothesis of a buckling mechanism generated by an imbalance in the growth speeds between the vertebrae and the surrounding structures as advocated by Shinoda et al.and Dickson et al.A finite element model of the spine together with the thoracic cage was maid to analysis growth deformation in the T4 to T10 vertebrae. The results yielded deformation that reduced thoracic kyphosis similar to what is observed in healthy children in early adolescence. In the process of increasing this deformation, the first to the fourth buckling modes were obtained, corresponding to the first bending mode in the coronal plane, the first rotation mode, the first bending mode in the sagittal plane, and the second bending mode in the coronal plane. The shape of the fourth mode agreed well with the clinical shapes. Considering the effect of posture on controlling the generation of these first bending and rotation modes and the absence of major muscles to correct the second bending mode, we presented a hypothesis that the 2nd bending mode in the coronal plane is one of the most likely etiological candidates in the mechanics of thoracic idiopathic scoliosis. To evaluate the growth rate and the shape of the fourth buckling mode precisely, nonlinear analysis using a more refined finite element model and experiment with a mechanical model were attemped. In the term of the research project, we made the finite element model and done a preliminary experiment. Sufficient results will be obtained in the future work.