Frequency of vertebral level involved listed according to aetiological group
| Level affected | Total group number (%) | BVO number (%) | TVO number (%) | PVO number (%) | Significance |
|---|---|---|---|---|---|
| Cervical | 16 (7.3) | 8 (7.6) | 0 | 8 (11.1) | NS |
| Thoracic | 70 (32) | 24 (22.8) | 27 (64.3)3-150 | 19 (26.4) | p < 0.0005 |
| Lumbar | 127 (58) | 68 (64.8) | 14 (33.3) | 45 (62.5) | NS |
| Multiple levels | 6 (2.7) | 5 (4.8) | 1 (2.4) | 0 | NS |
↵3-150 Significant difference with respect to the other groups. Abbreviations as in table 2.