Nonlinear Finite Element Analysis of Intervertebral Disc: A Comparative Study

Abstract

The aims of the study were i) to develop a finite element model of a functional spinal unit (FSU) without ligaments at cervical region, ii) to simulate different material properties of intervertebral disc for analysing degeneration and iii) to investigate the influence of disc degeneration on the biomechanical behaviour of a motion. To do so, two-dimensional computed tomography images of spine recorded from volunteer was converted into three-dimensional vertebrae model with different material properties section by section. Material properties of intervertebral disc are described nonlinear in finite element analysis. Moment was applied on superior endplate of vertebrae as 7.5 Nm. The boundary condition was described on the endplate of adjacent inferior vertebrae as fixed in space. Stress distribution over the nucleus and motions of the functional spinal unit were calculated using finite element analysis. The results were compared with physiological motions of functional spinal unit from literature. At the result, more realistic result of disc model was obtained by fluid filled cavity model with regard to maximum stress value on disc and intradiscal pressure. The fluid in the shell simulate incompressible feature like reality.