Table 1.
Material properties used in this study
| Material | Elastic modulus (MPa) | Poisson’s ratio (–) | Stiffness (N/mm) | Reference | Element type |
|---|---|---|---|---|---|
| Cortical bone | 10,000 | 0.3 | 8-node Hex | ||
| Cancellous bone (transverse isotropic) | 200/140 | 0.45/0.315 | [35] | 8-node Hex | |
| Posterior bony elements | 3,500 | 0.25 | [25, 33] | 8-node Hex | |
| Annulus fibrosus ground substance | Hyperelastic, neo-Hookean C10 = 0.3448, D1 = 0.3 |
[2] | 8-node Hex | ||
| Annulus fibers | Nonlinear and dependent on the distance to the disc center | [25, 33, 39] | Spring | ||
| Nucleus pulposus (healthy) | Incompressible | [26, 39] | Fluid | ||
| Nucleus pulposus (degenerated) | Compressible | [26] | Fluid | ||
| Ligaments | Nonlinear | [15, 26] | Spring | ||
| Pedicle screws (titanium) | 110,000 | 0.3 | Beam | ||
| Dynamic fixation device | 200 | Connector | |||
| Rigid fixation device (titanium) | 110,000 | 0.3 | 83,000 | Beam | |