Comparison of postoperative CT measurements between patients with and without FJP.
| Postoperative CT Measurement | Non-FJP Screw Placement (n = 60) | FJP Screw Placement (n = 8) | P Value |
| Sagittal angle of the C1-C2 facet joint | 20.8° ± 5.5° | 13.9° ± 4.4° | <0.01 |
| Sagittal angle of the C2 pedicle screw | 50.1° ± 6.1° | 55.5° ± 6.4° | 0.02 |
| Axial angle of the C2 pedicle screw | 17.9° ± 7.7° | 13.8° ± 3.4° | 0.02 |
| C2 pedicle screw length, mm | 23.5 ± 4.3 | 28.4 ± 3.9 | <0.01 |
| Bone mineral density of C2, Hounsfield units | 397 ± 134 | 305 ± 72 | 0.06 |
Abbreviations: CT, computed tomography; FJP, facet joint penetration.
Note: Data represented as mean ± SD.