The present study is conducted to develop a detailed FE model of spinal cord and to study its behaviour under various loading conditions. To achieve the goal, a previously developed and validated FE model of the middle cervical spine (C3-C5) is utilized. The model is further modified to investigate the stresses that the spinal cord in experiences during cervical spine motion segment in compression and flexion/extension loading modes. The resulting Von Misses stress and axial strain of the anterior and posterior surfaces of the cervical spinal cord are obtained from a set of elements along the C4-C5 disc space of the dural sheath, CSF and cord. The results show that in compression, the anterior surface of spinal cord experiences larger displacement, stress, and strain than those of the posterior surface. Conversely, the analyses show that in flexion\extension, the stresses, strains, and displacements are more pronounced in posterior segment of the spinal cord. In extension, the posterior disc bulge applies pressure onto the Posterior Longitudinal Ligament and thereby, applying local pressure on the spinal cord. The FE results show a stress concentration at the point of contact between disc and spinal cord. Furthermore, the FE results of flexion test show similar stress concentration characteristic at the point of contact. However, the local stress on spinal cord is more pronounced in flexion than extension at the C4-C5 area of spinal cord. It was also determined the compressive load resulted in the highest stress concentration on the spinal cord.
Continuous cervical spine kinematics during in vivo dynamic flexion-extension
