Surgical characteristics of study population.
| Characteristics | Metabolic | Nonmetabolic | P Value |
| Posterior approach | 39.7% | 29.0% | <0.001 |
| Anterior approach | 22.0% | 21.2% | <0.001 |
| Combined approach | 5.0% | 4.3% | <0.001 |
| Decompression | 68.8% | 55.0% | <0.001 |
| Fusion | 67.7% | 55.5% | <0.001 |
| 2- to 3-Level fusions | 51.8% | 43.1% | <0.001 |
| 4- to 8-Level fusions | 13.6% | 9.5% | <0.001 |
| >9-Level fusions | 0.7% | 1.4% | <0.001 |