A three-dimensional finite element model of a human ligamentous cervical spine was developed to study the mechanics of cervical injuries related to automotive crashes. Patran and LS-DYNA3D were used to create this preliminary model consisting of the cervical vertebrae, intervertebral discs, and biomechanically relevant spinal ligaments. Material properties were obtained from published experimental data. A rigid head was included to provide proper application of non-contact inertial loading.
Model development began with the generation of a single cervical motion segment. This model was subjected to a variety of loading conditions to provide a qualitative check of material properties and tissue interface conditions. Based on this motion segment model, a complete cervical model was developed including an attached rigid head.
Simulations were run for axial compression and frontal flexion. A small strain axial stiffness of 161.8 N/mm was determined for the case of pure z-displacement of the occiput. Large strain compression exhibited anterior bending of the cervical column and an overall stiffness value of 161.1 N/mm. Gross vertebral kinematics and deformation shapes compared well with experimental data from Pintar et al . The analytical flexion response predicted that head rotation would lag behind neck rotation by roughly 20 degrees, which is less than the roughly 30 degrees observed for volunteer sled test data.
Planned future enhancements include refinement of the vertebral geometry, improvement of the material definition for soft tissue components, and addition of musculature to the ligamentous spine model. An experimental study has begun which will provide essential data for these enhancements. Further validation of this model will be conducted upon completion of these experiments.