Clinical outcomes—VAS score and medication use.
| Outcome Measure | Estimated Mean (SE) | Overall P | ||
| Group A | Group B | Label | P | |
| Back VAS Score | ||||
| Preoperative | 4.417 (0.169) | 4.417 (0.169) | Group | 0.1574 |
| 1 mo | 3.042 (0.127) | 2.958 (0.127) | Time | <0.0001 |
| 3 mo | 2.375 (0.130) | 2.042 (0.130) | Group × time | 0.2331 |
| 6 mo | 1.792 (0.133) | 1.375 (0.133) | ||
| Leg VAS score | ||||
| Preoperative | 7.750 (0.186) | 7.375 (0.186) | Group | 0.0114 |
| 1 mo | 4.125 (0.186) | 3.375 (0.186) | Time | <0.0001 |
| 3 mo | 2.375 (0.174) | 2.208 (0.174) | Group × time | 0.004 |
| 6 mo | 2.375 (0.203) | 1.458 (0.203) | ||
| Medication Use, mg | ||||
| Preoperative | 137.500 (4.017) | 143.750 (4.017) | Group | 0.0492 |
| 1 mo | 100.000 (5.948) | 81.250 (5.948) | Time | <0.0001 |
| 3 mo | 72.917 (7.554) | 51.042 (7.554) | Group × time | 0.0125 |
| 6 mo | 52.083 (8.026) | 30.208 (8.026) | ||
Abbreviations: BESS, biportal endoscopic spine surgery; VAS, visual analog scale.
Note: Group A underwent conventional BESS technique. Group B underwent both-facet joint–preserving BESS technique. P < 0.05 was considered a statistically significant difference.