Three-dimensional finite element modeling of a cervical vertebra: an investigation of burst fracture mechanism.

Finite element modeling was used to study the mechanical behavior of a cervical vertebra under axial compressive loading. A three-dimensional (3-D) finite element (FE) model of a mid-cervical vertebra using inhomogeneous material properties was generated from quantitative computed tomographic (CT) scan data. This model improved upon previous vertebral FE models by using a highly refined mesh to represent the 3-D variation in material properties of vertebral bone. Traumatic loading of the vertebra was simulated by applying an axial compressive displacement through linear spring elements. Bone strength was computed from the CT scan data and compared with predicted stress. Based on the maximum shear stress theory of failure, the model predicts initiation of failure in the central cancellous region of the vertebral body. The type of fracture pattern predicted by the model is consistent with the typical cervical burst fracture that is seen clinically after compressive loading of the cervical spine. As such, we have developed a tool that can be useful for validating proposed fracture mechanisms in the cervical spine.