Study on pathogenic mechanism of idiopathic scoliosis by nonlinear buckling analysis

Abstract

The present paper describes the numerical results by the finite-element method of unstable phenomena of the spine induced by the growth of vertebral bodies in order to investigate the cause of the idiopathic scoliosis. In the previous study, through the linear buckling analysis using simple plate models, we confirmed the existence of the buckling phenomena, and made clear the region of geometrical parameters in which the buckling phenomena occur. These results support the buckling hypothesis as a cause of initiation of the idiopathic scoliosis. However, this theory is valid for infinitesimal deformation and is not applicable to estimate the stability for post-buckling behavior. In this study, we conduct post-buckling simulations caused by the growth of vertebral bodies considering the geometrical nonlinearity using the simple plate model and spine models with full width and half width. From the results, the existence of the non-linear buckling phenomena are confirmed in the simple plate model and the spine model with half width. Moreover, after the non-linear buckling phenomena, stable deformations are obtained excepting each one case in the simple plate model and the spine model with half width. However, the magnitudes of the post-buckling deformations are too small to explain the pathogenesis of the severe deformity observed in patients of idiopathic scoliosis.

Keywords

• biomechanics
• finite element method
• buckling
• finite deformation theory
• idiopathic scoliosis
• growth