TABLE 2.
Results of the ROC analysis for the 6 measurements considered for the diagnosis of atlantoaxial instability (differentiation between control group and AAI group)
| Measurements | Head Position | Cutoff value | Sensitivity (%) | Specificity (%) | PPV | AUC |
|---|---|---|---|---|---|---|
| VCI | Ext. | ≥0.16 | 100 | 94.54 | 0.8889 | 0.9974 |
| Flex. | ≥0.20 | 100 | 96.67 | 0.9583 | 0.9986 | |
| Atlantoaxial distance | Ext. | ≥4.1 | 81.25 | 69.86 | 0.5417 | 0.8179 |
| Flex. | ≥4.3 | 95.65 | 76.67 | 0.7586 | 0.9681 | |
| C1‐C2 Overlap | Ext. | ≤2.7 | 84.38 | 80.82 | 0.6585 | 0.9110 |
| Flex. | ≤1.8 | 95.65 | 90 | 0.88 | 0.9833 | |
| C1‐C2 Angle | Ext. | ≥176.9 | 90.63 | 82.19 | 0.6905 | 0.9456 |
| Flex. | ≥187.4 | 95.65 | 96.57 | 0.9565 | 0.9565 | |
| Basion‐Dens Interval | Ext. | ≥5.9 | 75 | 73.97 | 0.5581 | 0.8399 |
| Flex. | ≥3.0 | 95.65 | 96.67 | 0.9565 | 0.9957 | |
| DALR | Ext. | ≤0.24 | 21.88 | 100 | 1.0 | 0.6607 |
| Flex. | ≤0.29 | 21.74 | 100 | 1.0 | 0.7130 |
Abbreviations: AUC, area under the curve; DALR, dens‐to‐axis length ratio; PPV, positive predictive value; VCI, ventral compression index.