Cervical Spine Finite Element Models for Healthy Subjects: Development and Validation

Abstract

Finite element modeling is a popular method for predicting kinematics and kinetics in spine biomechanics. With the advancement of powerful computational equipment, more detailed finite element models have been developed for the various spine segments. In this study, five detailed finite element models of the cervical spine are developed and validated. The geometric boundaries of the vertebrae are determined from computed tomography (CT) scans of five female subjects. The models include the C2–C7 vertebrae, intervertebral discs, nuclei, endplates, and five major ligaments (anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), ligamentum flavum (LF), interspinous ligament (ISL), and capsular ligament (CL)). The ligaments follow nonlinear stress–strain curves whereas all other parts adopt linear material properties. All the material properties are taken from existing literature. The mesh convergence test is performed under flexion/extension. For flexion/extension motion, a pure moment is applied at the top surface of the odontoid process of the C2 vertebra while nodes at the bottom surface of the C7 vertebra are fixed in all directions. The models are extensively validated in flexion/extension, lateral bending, and axial rotation against experimental and finite element studies in the literature. Intervertebral rotation and range of motion are studied under different loading conditions found in the literature. This research also investigates intersubject variability for the cervical spine among five finite element models from five different subjects. Predicted angular displacements and ranges of motion of the current models are consistent with the literature. The validated models are expected to be applicable to simulate neckrelated trauma like whiplash and highg acceleration, among other scenarios.