Posterior Complex Contribution on Compression and Distraction Cervical Spine Behavior: A Finite Element Model

The relative contributions of the posterior elements on the human cervical spine behavior under axial compression and distraction were determined using the finite element modeling approach. This was accomplished by considering two structures: First, the intervertebral joint structure representing the anterior and posterior columns, including the C4–C6 vertebrae and the neighboring discs with the entire ligamentous complex; and second, the disc joint structure representing only the anterior column (vertebral bodies, discs and longitudinal ligaments). The anterior column sustained a higher share of the load than the posterior column under distraction. However, compression was shared equally among the anterior and the two posterior load bearing columns. The component internal stresses increased with posterior element removal. Consequently, inactivation or compromise in the posterior elements introduces additional internal loads or stresses in the anterior components which may accentuate degenerative changes or injure the cervical column. Thus, posterior complex integrity is critical for the load-carrying capacity of the cervical spine.