Spinal cord mechanics during flexion and extension of the cervical spine: a finite element study

The cervical spinal cord is at a great risk for injury during traumatic accidents occurring within people of relatively young age. Spinal cord injury can not be easily characterized clinically nor through in vitro testing. An understanding of cervical spinal cord deformation is important for defining an injury threshold of the spinal cord. Therefore, an analytical method may be beneficial for determining the response of the spinal cord response to external loads on the spine. We have developed a three-dimensional, non-linear finite element model to quantify physiologic strains and stresses in the cervical spinal cord placed in the ligamentous C5-C6 motion segment. Compressive loads along with flexion and extension moments were applied to the bony segment and not the cord itself. Motion data, shown in degrees of movement in flexion and extension calculated for the model showed a close representation to in vivo data. Von Mises stress plots and strains on the cervical spinal cord were computed. This model represents a first attempt by the authors to analytically quantify the mechanical response of the spinal cord to cervical spine injury.