Imaging measurement of circumferential cortical thickness of anterior entrance and anterior half of lower cervical pedicles and its application analysis / 第二军医大学学报

ABSTRACT

Objective To measure the circumferential cortical thickness of anterior entrance and anterior half of lower cervical pedicles on computed tomography (CT) images, providing a reference for accurate anterior cervical pedicle screws. Methods CT scanning was performed in 10 normal lower cervical vertebrae from fresh cadavers, and the coronal and sagittal reconstructed images were obtained. The images were then opened in AutoCAD-2007 software to perform quantitative measurement (accuracy was 0. 1 mm) using the “dimaligned function” of dimension menu, and measurement parameters included the thicknesses of superior, medial, inferior and lateral cortex of anterior entrance of pedicle (SAE. MAE. IAE and LAE. respectively), and thicknesses of superior, medial, inferior and lateral cortex of anterior half of pedicle (SPA, MPA, IPA and LPA, respectively). Results Average thicknesses of SAE. MAE. IAE. LAE, SPA, MPA. IPA, and LPA at left and right side from Q to C7 were (1. 9 + 0. 6) and (1. 9 + 0. 5) mm, (1. 9 + 0. 7) and (1.9+0. 4) mm. (2.4 + 0. 6) and (2. 4 + 0. 5) mm, (0. 9 + 0. 5) and (0. 9 + 0. 6) mm, (2. 3 + 0. 9) and (2. 3 +0. 7) mm, (2. 1 + 0. 5) and (2. 1 + 0. 6) mm, (2. 2+0. 8) and (2. 2+0. 7) mm, and (1. 0 + 0. 7) and (1. 0 + 0. 6) mm, respectively. There was no significant difference in same measurement parameter between left and right sides at same cervical level (P>0. 05). Single factor random block analysis of variance found LAE and LPA were significantly thinner than the other 6 parameters of the same side of same cervical vertebra (all P0. 05). Conclusion LAE and LPA are the thinnest among the 8 measurement parameters from C3 to C7, which suggests LAE and LPA have the weakest resistance to exotic force if resistance strength to exotic force is parallel to cortex thickness. We should avoid locating close to LAE when finding anterior entrance or close to LPA when inserting anterior cervical pedicle screws.