A biomechanical study of cervical disc degeneration in C4-C6 using finite element analysis

The C4-C6 region of the cervical spine is a common area of injury in the spinal column. Most of the injuries are caused due to accidents, sports etc. These injuries with increase in age can lead to slight, moderate and severe disc degeneration. As technology has advanced over the years, biomechanical finite element models are used instead of cadavers to study effects of progressive degeneration on the stress distribution. This study was conducted to develop a three dimensional finite element model of the C4-C6 human cervical spine structure using computed tomography scans and was validated against experimental data published earlier. The model was then used to produce progressive disc degeneration at the C4-C6 region by varying the material properties. Slight degeneration and moderate degeneration is obtained by modifying the material properties of nucleus pulposus and annulus fibrosus respectively. Severe degeneration was achieved by taking the material properties for maximum degeneration. The degenerated models were subjected to flexion, extension and lateral bending and the stress distribution on the anterior and posterior region were determined and compared with the intact model. Based on this study, the anterior region showed more increase in stress as compared to the posterior region with progressive degeneration.