Parametric finite element model of lower cervical spine (C3–C7) in sagital plane

Abstract

Cervical spine injuries could have life threatening consequences. This has made biomechanical studies on this region to be essentially needed. In this research a parametric 2D finite element model has been developed for lower cervical spine (C3-C7) in sagital plane. Being parametric, this model facilitates making changes in the geometrical sizes as well as omitting or modifying some parts of it in order to build a new model with special purposes. The first step of this research approach is to define 15 geometrical parameters for each vertebra. These parameters could be defined based on the anatomical similarities of the 3 rd to 7 th vertebra of cervical spine. The values differ from one vertebra to the other due to each one's morphology. Thus, parametric equations which describe the geometry of the model are derived. Then a Macro is programmed with Ansys Parametric Design Language (APDL), which runs under FEA software, ANSYSg.0. This model is made up of hard tissue (vertebral body, cortical and posterior elements bone) and soft tissue (intervertebral disks including nucleus, annulus and fibers, Ligaments with two interchangeably selected options of linear cable and nonlinear springs, and articular facets) which in spite of their integrity and continuity they preserve their independency to each other and to the changes in the size of parameters. A good fit was observed when validated the model with existed experimental results in sagital plane. The comparison shows more reliable results out of this 2D model than cited 3D complex models in flexion and extension.