The Hart-International Spine Study Group proximal junctional kyphosis severity scale.
| Parameter and Qualifier | Severity Scale |
| Neurological deficit | |
| None | 0 |
| Radicular pain | 2 |
| Myelopathy/motor deficit | 4 |
| Focal pain | |
| None | 0 |
| VAS ≤ 4 | 1 |
| VAS ≥ 5 | 3 |
| Instrumentation problem | |
| None | 0 |
| Partial fixation loss | 1 |
| Prominence | 1 |
| Complete fixation loss | 2 |
| Change in kyphosis/PLC integrity | |
| 0°–10° | 0 |
| 10°–20° | 1 |
| >20° | 2 |
| PLC failure | 2 |
| UIV/UIV+1 fracture | |
| None | 0 |
| Compression fracture | 1 |
| Burst/chance fracture | 2 |
| Translation | 3 |
| Level of UIV | |
| Thoracolumbar junction | 0 |
| Upper thoracic spine | 1 |
Abbreviations: PLC, posterior ligamentous complex;UIV, uppermost instrumented vertebra; VAS, visual analog scale.
Note: Reprinted with permission from Hart et al.13