| Spinal alignment/Roussouly type | Observed (%) | Normal population (%) | P-value |
| 1 | 17 | 21.3 | n.s. |
| 2 | 62.2 | 11.3 | <0.001 |
| 3 | 17 | 37.5 | n.s. |
| 4 | 3.8 | 30 | <0.001 |