经骶骨纵向固定腰骶滑脱的解剖学研究

Anatomic study for lumbosacral cannulated screws placement

目的 对骶骨进行形态学测量 ,研究后路空心钉经骶骨纵向固定腰骶部的安全性。方法 对 2 0例干燥骶骨标本进行CT扫描 ,并进行多平面重建 (MPR)分析 ,测量S1水平骶骨侧块中心的长、宽及面积 ,确定该固定方法的空心钉钉道的长度、安全方向和范围。结果 2 0例骶骨标本中 ,该固定方法的最窄部分位于S1神经孔水平 ,其几何中心的平均长度为 (37.31± 4 .2 1)mm(2 9～ 4 6 .7mm) ,平均宽度为 (2 1.2 9± 3.5 7)mm(16 .3～ 2 7.4mm) ,平均面积为 (6 .31± 1.2 3)cm2 。通过测量和分析 ,空心钉在矢状面和冠状面的平均最小角度分别为 2 6 .2 9°(2 4 .1°～ 31.3°)和 4 3.6 5°(2 6 .0°～ 5 4 .5°) ,空心钉的平均长度为 85 .2 8mm。结论 相关解剖学数据表明 ,只要进钉的方向及角度正确 ,空心钉经骶骨纵向固定的通道位于骶骨内。术前行CT检查或三维重建 ,制定个体化固定方案 ,该方法可安全地应用于临床。

Objective To measure and analyze the dimensions of the sacrum for safe placement of lumbosacral longitudinal cannulated screws, as well as feasible localization of the screw passage. Methods 20 dry sacra were obtained for anatomic CT evaluation. Helix CT scans of the sacrum and Multiple Plane Reconstruction (MPR) were performed. Computer analysis and measurements of sacral geometry were used to determine the narrowest portion of the bony sacral ala and the safe passage of lumbosacral screws. The maximum height, maximum width, area of the sacral ala through its geometric center in cross section, the angle in coronal and sagittal plane and the optimal length of the screws were measured. Results The narrowest portion of the sacral ala in all sacra was consistently located at the level of the first sacral foramen. The average maximum height at the geometric center in cross-section was 37.31 mm, while the average width was 21.29 mm and the average area was 6.31cm2. The minimal angles in coronal and sagittal plane of the screw passage were 26.29°(24.1°～31.3°) and 43.65°(26.0°～54.5°)respectively, and the optimal length of the screws was 85.28 mm. Though the variability of the sacral alar geometry was present, there was ample cross-sectional area to accommodate the lumbosacral cannulated screws if correctly positioned. Conclusion According to the data above, with proper surgical technique and good preoperative and intraoperative imaging, lumbosacral cannulated screws may be safely contained intraosseously through the sacrum longitudinally. Other than the knowledge of sacral anatomy, the value of the CT model with three-dimension reconstruction for the single individual may conduct to ensure the safe and good clinical results with lumbosacral cannulated longitudinal placement.