Lumbar spine finite element model for healthy subjects: development and validation

Abstract

Finite element (FE) method is a proven powerful and efficient tool to study the biomechanics of the human lumbar spine. However, due to the large inter-subject variability of geometries and material properties in human lumbar spines, concerns existed on the accuracy and predictive power of one single deterministic FE model with one set of spinal geometry and material properties. It was confirmed that the combined predictions (median or mean value) of several distinct FE models can be used as an improved prediction of behavior of human lumbar spine under identical loading and boundary conditions. In light of this improved prediction, five FE models (L1-L5 spinal levels) of the human lumbar spine were developed based on five healthy living subjects with identical modeling method. The five models were extensively validated through experimental and computational results in the literature. Mesh convergence and material sensitivity analysis were also conducted. We have shown that the results from the five FE models developed in this paper were consistent with the experimental data and simulation results from the existing literature. The validated modeling method introduced in this study can be used in modeling dysfunctional lumber spines such as disc degeneration and scoliosis in future work.

Biomechanical evaluation of strategies for adjacent segment disease after lateral lumbar interbody fusion: is the extension of pedicle screws necessary?

“…For the stress sensitivity analysis, the intact lumbar spine model was tested in the following loading directions: compression (150 N) and Flx (10.0 N-m). According to Xu et al, the parameters were linearized to perform the stress sensitivity analysis for the model [24]. To save simulation time, the analysis did not involve annulus fibres and ligaments since Jebaseelan et al, Fagan et al and Pianigiani et al considered that the material properties of fibres and ligaments were not sensitive [25][26][27].…”

“…As Xu et al suggested that ROM was a sensitivity response in the stress sensitivity analysis. Thus, ROM was chosen to test in this study [24]. Since the stress or strain results were focused on the L3-4 level, the ROM at the L3-4 level obtained by the nonlinear model, linearized basic model, high-value model and low-value model were compared.…”

Variations Among Human Lumbar Spine Segments and Their Relationships to In Vitro Biomechanics: A Retrospective Analysis of 281 Motion Segments From 85 Cadaveric Spines

“…Several factors make this retrospective analysis unique, including: (1) the large number of specimens involved (281 motion segments from 85 spines); (2) known demographics, material and geometric values;(3) biomechanical properties obtained using a consistent and precise test method (including ROM as well as the subcomponents LZ and SZ); and (4) the analysis of correlations between all of these variables. Previous similar studies, some of which also included a large number of specimens, 4,6 did not consider all of the variables analyzed in the current study.…”

“…Finite element models of the lumbar spine developed from specimen-specific geometry are often validated using experimental data presented in the literature. 1,2 These data are frequently taken from a limited number of spines from both sexes with a high average age, resulting in large standard deviations, which potentially makes validation steps easier. However, based on our current findings, we propose that computational models that use specimen-specific spinal geometry may not be as accurate at predicting biomechanical outcomes as models that incorporate specimen-or at least population-specific material properties.…”

“…In some published studies involving finite element models of spinal segments, researchers have configured the computer model to mimic experimental behavior seen in limited data sets or to match average behavior from metadata collected using a large number of samples but with inconsistent testing methods. 1,2 For instance, some published experimental data describing the biomechanical behavior of intact and normal lumbar spinal motion segments include specimens from only one sex, 3 specimens without known material or geometric motion segment properties, [3][4][5] or limited donor demographic variables. 6 The load conditions used during these studies vary as well, such as the maximum applied load magnitude (5 to 8 N m), the loading rate, and the possible addition of a compressive preload during bending.…”