Abstract
Finite element (FE) models have frequently been used to analyze spine biomechanics. Material parameters assigned to FE spine models are generally uncertain, and their effect on the characterization of the spinal components is not clear. In this study, we aimed to analyze the effect of model parameters on the range of motion, stress, and strain responses of a FE cervical spine model. To do so, we created a computed tomography-based FE model that consisted of C2-C3 vertebrae, intervertebral disc, facet joints, and ligaments. A total of 32 FE analyses were carried out for two different elastic modulus equations and four different bone layer numbers under four different loading conditions. We evaluated the effects of elastic modulus equations and layer number on the biomechanical behavior of the FE spine model by taking the range of angular motion, stress, and strain responses into account. We found that the angular motions of the one- and two-layer models had a greater variation than those in the models with four and eight layers. The angular motions obtained for the four- and eight-layer models were almost the same, indicating that the use of a four-layer model would be sufficient to achieve a stress value converging to a certain level as the number of layers increases. We also observed that the equation proposed by Gupta and Dan (2004) agreed well with the experimental angular motion data. The outcomes of this study are expected to contribute to the determination of the model parameters used in FE spine models.
Highlights
Due to the ethical concerns and the requirement of invasive methods, determining the in vivo stress and strain values that occur on the vertebrae under different loading conditions is challenging [1]
The number of layers was found as an effective parameter in the calculation of the angular motion, while the major differences in terms of angular motion were found between oneand two-layer models
We aimed to analyze the effects of variations in elastic modulus and layer number on the model-predicted angular motion, stress, and strain values that occurred at the C2/C3 level of the finite element (FE) spine model under various loading modes
Summary
Due to the ethical concerns and the requirement of invasive methods, determining the in vivo stress and strain values that occur on the vertebrae under different loading conditions is challenging [1]. The finite element-based computational modeling and simulation approach provide a practical and efficient solution to this problem. In many FE-based studies, the values of the elastic modulus were calculated by using these equations [10,11,12], while very few of them focused on the spinal region [9, 13, 14]. The reliability of these equations is still controversial, and a consensus on the use of these equations has not yet been reached [15]
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