Development of a CT-based 3D finite element model of the whole cervical spine with occiput: Insights into sagittal balance, disc pressure, and facet joint forces

The majority of previously published cervical spine models used in finite element (FE) analysis usually include only parts of motion units, resulting in differences in the realistic response of the whole cervical spine. This study aimed to develop a geometrically accurate, comprehensive, three-dimensional (3D) FE model for the entire cervical spine. A 3D FE model of the full cervical spine was constructed based on CT data. The predicted range of motion (ROM) for each segmental motion of the cervical spine was compared with previous research. Additionally, the present FE model was used to evaluate von Mises stress in the bones, intervertebral disc pressure (IDP), and facet joint force to analyze the biomechanical effects under physiological loading. The complete FE model consisted of 2,218,790 elements and 3,332,459 nodes, including 7 cervical vertebrae, occiput, 5 intervertebral discs, 13 ligaments, and 7 pairs of facet joints. The ROMs obtained were consistent with published experiments in terms of both value and tendency. The IDP and facet joint force was asymmetric under flexion-extension, while symmetric under axial rotation and lateral bending. The validation of our developed model coincided with experimental studies and proved to be more convincing than models that only considered parts of motion units.