Table 4.
The von-Mises stress on the structures of the L4–5 spine in the lateral bending 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 | 1.432 | 1.409 | 1.416 | 1.14∗ | 1.467 | 1.422 | 1.416 | 3.62∗ |
| L5 | 1.062 | 1.052 | 1.055 | 0.69∗ | 1.145 | 1.095 | 1.055 | 8.56∗ | |
| Cancellous bone | L4 | 0.083 | 0.078 | 0.074 | 12.24∗ | 0.071 | 0.073 | 0.074 | −3.65 |
| L5 | 0.093 | 0.091 | 0.089 | 4.37∗ | 0.091 | 0.090 | 0.089 | 2.54∗ | |
| Posterior bone | L4 | 0.449 | 0.494 | 0.542 | −17.29 | 0.485 | 0.522 | 0.542 | −10.51 |
| L5 | 0.774 | 0.766 | 0.761 | 1.70∗ | 0.775 | 0.768 | 0.761 | 1.87∗ | |
| Endplate (upper) | L4–5 | 1.096 | 1.235 | 1.345 | −18.51 | 1.346 | 1.354 | 1.345 | 0.04∗ |
| Endplate (lower) | L4–5 | 0.540 | 0.513 | 0.507 | 6.36∗ | 0.544 | 0.519 | 0.507 | 7.19∗ |
| Disc (outer) | L4–5 | 0.175 | 0.178 | 0.183 | −3.94 | 0.187 | 0.186 | 0.183 | 2.53∗ |
| Disc (inner) | L4–5 | 0.041 | 0.044 | 0.046 | −10.23 | 0.046 | 0.047 | 0.046 | 0.34∗ |
∗ indicates that a larger load than normal was received when the disc height was reduced by 50%.