Validation of a finite element model of the young normal lower cervical spine.

A Finite Element Model (FEM) of the young adult human cervical spine has been developed as a first step in studying the process of spondylotic degeneration. The model was developed using normal geometry and material properties for the lower cervical spine. The model used a three-zone composite disc annulus to reflect the different material properties of the anterior, posterior, and lateral regions of the annulus. Nonlinear ligaments were implemented with a toe region to help the model achieve greater flexibility at low loads. The model was validated against experimental data for normal, nondegenerated cervical spines tested in flexion and extension, right and left lateral bending, and right and left axial rotation at loads of 0.33, 0.5, 1.0, 1.5, and 2.0 Nm. The model was within in vitro experimental standard deviation corridors 100% of the load range for right and left lateral bending. The model was within 80% of the load response corridors for extension and flexion with a deviation <0.3 degrees from the SD corridors. For axial rotation, the model was within 70% of the SD corridors for left axial rotation within 83% of right axial rotation responses. The deviation from SD corridors for axial rotation was generally <0.2 degrees.