Table 3.
The von-Mises stress on the structures of the L4‐5 spine in the extension 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 | 1.5655 | 1.6992 | 1.8453 | −15.16 | 2.1541 | 1.9900 | 1.8453 | 16.73∗ |
| L5 | 1.0263 | 1.0463 | 1.0692 | −4.01 | 1.2675 | 1.1655 | 1.0692 | 18.55∗ | |
| Cancellous bone | L4 | 0.0816 | 0.0803 | 0.0809 | 0.92∗ | 0.0881 | 0.0853 | 0.0809 | 8.92∗ |
| L5 | 0.1007 | 0.0963 | 0.0926 | 8.66∗ | 0.0982 | 0.0953 | 0.0926 | 6.05∗ | |
| Posterior bone | L4 | 0.5631 | 0.6448 | 0.7204 | −21.83 | 0.7227 | 0.7293 | 0.7204 | 0.32∗ |
| L5 | 0.6623 | 0.6795 | 0.6970 | −4.97 | 0.7354 | 0.7169 | 0.6970 | 5.51∗ | |
| Endplate (upper) | L4-5 | 1.4776 | 1.7772 | 2.0771 | −28.86 | 2.2418 | 2.1836 | 2.0771 | 7.93∗ |
| Endplate (lower) | L4-5 | 0.5666 | 0.6428 | 0.7180 | −21.08 | 0.8999 | 0.8127 | 0.7180 | 25.34∗ |
| Disc (outer) | L4-5 | 0.1739 | 0.1857 | 0.1972 | −11.79 | 0.2124 | 0.2095 | 0.1972 | 7.71∗ |
| Disc (inner) | L4-5 | 0.0371 | 0.0438 | 0.0481 | −22.80 | 0.0522 | 0.0516 | 0.0481 | 8.61∗ |
∗ indicates that a larger load than normal was received when the disc height was reduced by 50%.