Finite element modeling and comparative mechanical analysis of cervical facet joints in humans and macaques

Purpose: To establish a finite element model of the adult cervical spine and the adult macaque cervical spine and to compare the stress and displacement changes between the two under six working conditions through finite element analysis around the stress characteristics of the facet joint, to provide a theoretical basis for clinical vertebral body replacement. Methods One 40-year-old adult volunteer and one 7-year-old adult male macaque were selected and subjected to spiral CT thin-layer scans, respectively. Moreover, the original cervical spine CT data were imported into Mimics 21.0 to establish a three-dimensional model. The models of cervical spine segments, discs, and ligaments were optimized, assigned, and assembled to organize the mesh. Finally, using Abaqus, the cervical spine finite element model was loaded with 75 N additional load and 1 N-m external dip moment. To discover the mechanical trends and differences by conducting the automated comparison analysis under six working conditions of anterior flexion, posterior extension, left and right lateral flexion, and left and proper rotation. Results Both human and macaque cervical vertebrae have cervical facet joints. Furthermore, finite element modeling comparison revealed that the uncovertebral joints' stress and displacement changes were generally consistent between the two. The stress and displacement concentrations were all at C6. There was a significant difference between the human and the macaque. Conclusions Macaques can be the best alternative animal model for clinical studies of the cervical spine, providing a theoretical basis for clinical cervical vertebral body replacement and other aspects.