Influence of Vertebra Stiffness in the Finite Element Analysis of the Intervertebral Disc

Abstract

Spine finite element models are an essential tool to study the degeneration of the intervertebral disc (IVD). Due to the complex geometry of the vertebras, the anisotropy and heterogeneity of the tissues, and the contact and material nonlinearities [1], spine models demand high computational resources. Considering the relatively low stiffness of the IVD compared to that of the vertebrae, we hypothesized that finite element stress and stress distributions of the IVD do not change substantially if the vertebras are modeled as rigid bodies. This simplification in spine models may considerably reduce the solution time when the interest is the analysis of the IVD.

How the height and the area of the annulus fibrosus affect the range of motion behavior: A stochastic analysis

“…30 These papers have shown that these simplifications have little influence over the final results, for instance, the maximum stress in the annulus fibrosus and the intradiscal pressure only changed about 2% when compared to the results of an elastic model for the bones and endplates. 28…”

“…With respect to the simplification of the endplates as rigid bodies, this assumption has been adopted in models reported by Dı´az et al, 28 Moramarco et al, 29 and Cegon˜ino et al 30 These papers have shown that these simplifications have little influence over the final results, for instance, the maximum stress in the annulus fibrosus and the intradiscal pressure only changed about 2% when compared to the results of an elastic model for the bones and endplates. 28…”