Table 5.
The von-Mises stress on the structures of the L4–5 spine in the axial rotation mode when the disc height was reduced to 75% and 50% compared to normal (100%).
| Component | The 50% anterior disc model, MPa (a) | The 75% anterior disc model, MPa (b) | The 100% anterior disc model, MPa (c) | Rate of change [(a-c)/c ∗ 100] (%) | The 50% posterior disc model, MPa (d) | The 75% posterior disc model, MPa (e) | The 100% posterior disc model, MPa (f) | Rate of change [(d-f)/f ∗ 100] (%) | |
|---|---|---|---|---|---|---|---|---|---|
| Cortical bone | L4 | 0.781 | 0.772 | 0.809 | −3.48 | 0.982 | 0.877 | 0.809 | 21.45 |
| L5 | 1.249 | 1.240 | 1.239 | 0.86∗ | 1.282 | 1.254 | 1.239 | 3.50∗ | |
| Cancellous bone | L4 | 0.069 | 0.064 | 0.059 | 17.71∗ | 0.053 | 0.056 | 0.059 | −9.58 |
| L5 | 0.091 | 0.090 | 0.088 | 2.33∗ | 0.089 | 0.089 | 0.088 | 0.08∗ | |
| Posterior bone | L4 | 0.388 | 0.457 | 0.524 | −25.98 | 0.488 | 0.513 | 0.524 | −6.89 |
| L5 | 1.195 | 1.198 | 1.203 | −0.74 | 1.205 | 1.205 | 1.203 | 0.12∗ | |
| Endplate (upper) | L4–5 | 0.420 | 0.466 | 0.629 | −33.18 | 0.856 | 0.747 | 0.629 | 36.12∗ |
| Endplate (lower) | L4–5 | 0.376 | 0.342 | 0.331 | 13.67∗ | 0.378 | 0.343 | 0.331 | 14.23∗ |
| Disc(outer) | L4–5 | 0.125 | 0.122 | 0.118 | 5.88∗ | 0.122 | 0.121 | 0.118 | 3.26∗ |
| Disc(inner) | L4–5 | 0.024 | 0.023 | 0.024 | 0.38∗ | 0.026 | 0.025 | 0.024 | 11.09∗ |
∗ indicates that a larger load than normal was received when the disc height was reduced by 50%.