Using the finite element method to determine the influence of age, height and weight on the vertebrae and ligaments of the human spine

Abstract

This study uses the Finite Element Method (FEM) to analyze the influence of age, height and weight on the vertebrae and ligaments of the human functional spinal unit (FSU). Two different artificial segments and the influence of the patient’s age, sex and height were considered. The FSU analyzed herein was based on standard human dimensions. It was fully parameterized first in engineering modelling format using CATIA© software. A combination of different elements (FE) were developed with Abaqus© software to model a healthy human FSU and the two different sizes of artificial segments. Healthy and artificial FSU Finite Element models (FE models) were subjected to compressive loads of differing values. Spinal compression forces, posture data and male/female anthropometry were obtained using 3DSSPP© software Heights ranging from 1.70 to 1.90 meters; ages, between 30 and 80 years and body weights between 75 and 90 kg were considered for both men and women. Artificial models were based on the Charité prosthesis. The rtificial prosthesis consisted of two titanium alloy endplates and an ultra-high-molecular-weight polyethylene (UHMWPE) core. An analysis in which the contacts between the vertebrae and the intervertebral disc, as well as the behavior of the seven ligaments, were taken into consideration. The Von Mises stresses for both the cortical and trabecular bone of the upper and lower vertebrae, and the longitudinal stresses corresponding to the seven ligaments that connect the FSU were analyzed. The stresses obtained for the two geometries that were studied by means of the artificial FE models were very similar to the stresses that were obtained from healthy FE models.