下颈椎椎弓根前入口及前半四壁皮质厚度的影像学测量及应用分析

目的 对下颈椎椎弓根前入口及椎弓根前半的四壁皮质厚度行CT影像学测量,为前路椎弓根钉准确置入提供参考.方法 对10例正常新鲜尸体的颈椎标本进行CT扫描并重建图像.用AutoCAD 2007软件的“对齐标注”测量下颈椎椎弓根前人口上(SAE)、内(MAE)、下(IAE)和外(LAE)以及椎弓根前半上(SPA)、内(MPA)、下(IPA)和外(LPA)的皮质厚度(精确度0.1 mm),并对测量结果进行比较分析.结果 C3～7左侧和右侧的平均SAE、MAE、IAE、LAE、SPA、MPA、IPA及LPA厚度分别为(1.9±0.6)和(1.9±0.5)mm、(1.9±0.7)和(1.9士0.4) mm、(2.4±0.6)和(2.4±0.5) mm、(0.9±0.5)和(0.9±0.6) mm、(2.3±0.9)和(2.3±0.7)mm、(2.1士0.5)和(2.1±0.6) mm、(2.2±0.8)和(2.2±0.7) mm及(1.0±0.7)和(1.0士0.6)mm.同一颈椎同一测量指标的左、右侧比较差异均无统计意义(P＞0.05).对同一颈椎同侧的不同测量指标行单因素随机区组方差分析,结果示LAE与LPA最薄,均薄于其他6个测量指标,差异有统计学意义(P均＜0.01),而LAE与LPA厚度之间差异无统计学意义(P＞0.05).结论 下颈椎椎弓根LAE及LPA较其他侧壁皮质菲薄,如皮质厚度与抵抗外力强度一致,则LAE和LPA抵抗外力的强度最小.提示颈前路椎弓根螺钉固定寻找前入口时应避免靠近LAE,在螺钉置入过程中应避免靠近LPA.

Imaging measurement of circumferential cortical thickness of anterior entrance and anterior half of lower cervical pedicles and its application analysis

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 C₃ 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 P<0.01), while LAE and LPA were not significantly different (P>0.05). 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.