Effect of Sharpey's Fibers on the Stress Distribution in the Anulus Fibrosus of an Intervertebral Disc Subjected to Compression

Abstract

Theoretical analyses of stress and strain in intervertebral discs have received little attention in the scientific literature, in favor of experimental and finite element studies. Constitutive modeling using the finite element method is effective and powerful. However, only few model variables can be verified by experimental measurements which may result in insufficient model validation. Triangulation of methodologies reinforces model reliability, and could be achieved by developing an analytical approach. This study examines the potential of thin-shell theory and beam on elastic foundation theory for simulation of the anulus fibrosus multi-shell structure and the endplate anchorage of lamellae via Sharpeys fibers. The model is based on a simplified axisymmetric disc subjected to axial compression and takes into account large deformations of the disc. The performance of the model was compared to that of a simplified finite element model. The two models responded similarly, and the results demonstrate that beam on elastic foundation theory is applicable to simulate Sharpey’s fiber effects and should be considered for use in the analytical study of intervertebral discs. Future research should focus on realistic representation of the complex changes in lamellar geometry due to large deformation, and on inclusion of material anisotropy and hyperelasticity, asymmetric geometry and complex loadings.
Copyright © 2016 Praise Worthy Prize - All rights reserved.