Spine model for disc replacement

Total disc replacement (TDR), a new surgical technique for treating degenerative disc disease, has resulted in many reliable clinical outcomes. The biomechanical effects of TDR need to be investigated to evaluate the long-term impact of using such devices. The finite element method (FEM) can simulate the various geometries and materials of the prosthesis and predict the range of motion (ROM) and many other biomechanical parameters before and after operation, while reducing both research time and expense in comparison to cadaver and animal studies. Therefore, we developed computational models that can be used to understand cervical spine biomechanics and evaluate the long-term effectiveness of disc prostheses. A three-dimensional, nonlinear FEM of intact human C3-C7 segments was developed from a reconstruction of computer tomography (CT) images. Specifically, the C3-C7 segments were chosen because of the large amount of clinical and experimental data available for these joints. The geometrically accurate spinal FE model consisted of five separate vertebrae, four intervertebral discs, and five kinds of ligaments. The intact model was validated by comparing the ROM predicted by FEM to in vitro experimental data. An artificial disc prosthesis (ProDisc-C, Synthes) was then integrated into the C3-C7 model in ABAQUS to make up a complete spine model for disc replacement. This validated FE model can be used to investigate the biomechanical effects of total disc replacement, such as facet force and tension force in ligaments.