[Imaging measurement and clinical significance of the angle between the axis of pedicle and the plane of lamina in lower cervical vertebra].

To explore the imaging measurement and clinical significance of the angle between the axis of pedicle and the plane of lamina in lower cervical vertebra.
 Methods: Three dimensional reconstruction of CT scan was performed in 30 patients with cervical deformity, and the angle between the axis of pedicle and the plane of lamina was measured with the specific reconstructed CT image of C3-C7.
 Results: 1) The left and right transverse angle of C3-C7 between the axis of pedicle and the ipsilateral plane of lamina were 98.3°±6.3°, 98.0°±5.1°, 97.5°±6.9°, 95.1°±5.0°, 85.8°±5.4° and 96.7°±8.2°, 98.7°±7.1°, 97.8°±3.6°, 93.2°±6.2°, 86.8°±5.7°, respectively, which showed a gradual decreasing trend. Meanwhile the angle of C3-C6 was more than 90 degrees and C7 was less than 90 degrees. In addition to C6 with C3 and C7 with other segments, the rest of the differences between the sections was not statistically significant (all P>0.05). 2) The left and right transverse angle of C3-C7 between the axis of pedicle and the pedicle of vertebral arch of lamina were 0.2°±4.5°, 1.2°±7.2°, -0.8°±6.8°, -3.3°±5.4°, -14.7°±4.0° and -1.6°±5.4°, 1.9°±4.6°, -0.5°±6.0°, -4.6°±5.3°, -13.7°±3.4°, respectively, which showed a first increasing and then reducing trend. Meanwhile the angle of C4 was maximum angle. In addition to C6 with C3, C6 with C4, and C7 with other segments, the differences between the sections was not statistically significant (all P>0.05). 3) The left and right sagittal angle of C3-C7 between the axis of pedicle and the ipsilateral plane of lamina were 77.7°±7.6°, 77.0°±7.1°, 85.3°±8.4°, 94.1°±2.2°, 94.9°±3.8° and 78.5°±7.1°, 76.2°±6.2°, 86.4°±6.4°, 94.0°±2.7°, 95.6°±3.8°, respectively, which showed a gradual increasing trend. The angle of C3-C4 was less than 90 degrees. C5 showed large variation and C6-C7 was more than 90 degrees. In addition to C3 with C4 and C6 with C7, the differences between the sections was statistically significant (all P<0.05). There was no significant difference between the two sides of the above indexes (all P>0.05).
 Conclusion: In low cervical vertebra, there is a certain angle relationship between the axis of pedicle and the plane of lamina, which can provide reference for the clinical determination of angle of pedicle screw insertion.