自行研制的经皮胸腰椎椎弓根置钉三维定位器应用的可行性实验研究

A three-dimensional guiding instrument for percutaneous insertion of thoracolumbar pedicle screws

目的通过与“徒手”置钉进行比较，探讨自行研制的经皮胸腰椎椎弓根置钉三维定位器辅助在脊柱标本上进行经皮椎弓根穿刺的可行性。方法对新鲜保留皮肤软组织的脊柱标本2具（32个椎体）行胸腰椎序列CT扫描，使用Mimics13．1软件确定椎弓根轴心片，测定水平面椎弓根螺钉植入角度（TSA）及矢状面椎弓根螺钉植入角度（SSA）。定位皮肤穿刺点，对应调节水平面及矢状面角度指示器刻度指导穿刺。椎弓根随机分为两组：一侧为自行研制的经皮胸腰椎椎弓根置钉三维定位器辅助组（定位器组），对侧为“徒手”置钉组（徒手组）。定位器组在定位器及x线辅助下穿刺，徒手组在C型臂影像增强系统辅助下予“徒手”技术穿刺，置入克氏针，C型臂x线机证实穿刺成功。行椎弓根CT扫描，测量2种方法穿刺的实际TSA角及SSA角，将术前测定的椎弓根TSA角及SSA角与术后实际TSA角及SSA角对比，计算偏差率；比较两组的偏差率和x线曝光次数。结果定位器组和徒手组的穿刺TSA角偏差率平均分别为10．83％±3．41％和19．08％±4．21％，差异有统计学意义（P〈0．05）；定位器组和徒手组的穿刺SSA角偏差率平均分别为13．13％±4．37％和21．15％±6．78％，差异有统计学意义（P〈0．05）。定位器组和徒手组接受x线辅助的次数平均分别为（3．0±1．2）次和（5．3±1．6）次，差异有统计学意义（P〈0．05）。结论与“徒手”置钉相比，应用自行研制的经皮胸腰椎弓根置钉三维定位器可有效提高手术准确度、降低手术难度、减少x线暴露。

Objective To test a self-designed 3-D guiding instrument for percutaneous insertion of thoracolumbar pedicle screws in cadaveric vertebrae. Methods Two fresh eadaveric vertebral specimens with skin and soft tissue were used first for standard CT lateral scanning of T1 to L4. Software Mimicsl3. 1 was used to create axial images of pedieles of vertebral arch. The points of percutaneous insertion of thoracolumbar pedicle screws, transverse screw angles （TSA） and sagittal screw angles （SSA） were measured. Thirty-two vertebral bodies were divided randomly into 2 equal groups for guiding instrument insertion and manual insertion with the aid of C-arm fluoroscopy. The quality of insertion was evaluated by postoperative CT scans. Angular deviations were determined by comparing the preoperative and postoperative TSA and SSA for the 2 groups. X-ray exposures were also compared between the 2 groups. Results The TSA angular deviation rate was （ 10.83 ± 3.41 ） % for the guiding instrument insertion group and （ 19.08 ± 4.21 ） % for the manual insertion group. The SSA angular deviation rate was （13.13 ± 4.37） % for the guiding instrument insertion group and （21. 15 ±6. 78） % for the manual insertion group. The guiding instrument insertion group needed 3.0 ± 1.2 X-ray exposures while the manual insertion group had 5.3 ± 1.6 X-ray exposures. All the differences were statistically significant. Conclusion The 3-D guiding instrument can facilitate the percutaneous insertion of the thoracolumbar pedicle screws by improving operation accuracy and reducing operation difficulty and X-ray exposures as well.