Finite element analysis of a patient-specific model of the lumbar spine behaviour

M. Mesbah, A. Barkaoui, H. Chiali

Abstract: The finite element modelling (FE) of human tissue plays a significant role in the biomechanics by offering a new prominent quantification and simulation of the functional behaviour of the human body in various physiology conditions. This study focused on the development of an effective process for generating a simplified anatomical FE model of the lumbar spine. The proposed model of the lumbosacral spine L1-S1 was subjected to pure and combined loading modes and validated compared to in vitro and in vivo measurements. This validation was carried out by comparing the results with previous FE models and literature for combined loading: moment + axial follower load of 7.5 Nm + 150 N to predict the behaviours of the functional spinal unit FSU L4-L5. The validation of the whole lumbar spine was performed by determining the range of motion ROM under only pure moment of 7.5 Nm. The presented results provide a good agreement with FE median of previous FE models in different loading cases. The predicted L1-L5 rotations demonstrate a fair agreement with in vitro ranges except smaller values for flexion-extension, 0.3~3° comparing to FE median, 0.3~1.5 ° for lateral bending and 0.3~1.6° for axial rotation for all levels comparing to in vitro median. The facet joint forces fit the reported median in vivo and median FE values, 36N in extension and 63N in lateral bending. The Intradiscal pressures are in range of in vivo and in vitro values under compressive loads. Although, the nucleus pressures were smaller than those of reported in vivo results for lateral bending. The incorporation of simplification techniques will allow us to generate more thorough models of the lumbar spine and boost model applicability.

Series on Biomechanics, Vol.33, No. 3(2019), 27- 39

Keywords: biomechanics; Finite element method; lumbar spine; range of motion; validation

Date published: 2019-10-22