标杆型3D打印导板辅助寰枢椎椎弓根置钉准确度分析

Accuracy assessment of a 3D printed navigational guiding template for atlantoaxial pedicle screw placement

目的探讨标杆型3D打印导板辅助寰枢椎椎弓根置钉的可行性，并进行置钉准确度分析。方法2014年6月一2015年8月，本院收治寰枢椎脱位患者21例，男12例，女9例；年龄12~54岁，平均42.6岁。术前使用Mimics 17.0软件和3-matic 9.0软件为每例患者制作标杆型3D打印导板，术中使用标杆型3D打印导板辅助寰枢椎椎弓根置钉，术后患者行颈椎CT平扫。在Mimics 17.0软件中，将手术前后的寰枢椎模型及螺钉配对拟合，调整空间坐标轴，测量并比较术前预设钉道与术后实际钉道的内倾角、头倾角、进钉点坐标。结果21例患者手术顺利，手术时间（ 193 ± 51 ) min,术中出血量（ 384 ±127) mL。共置人寰椎椎弓根螺钉30枚，枢椎椎弓根螺钉42枚。除2 枚寰椎椎弓根螺钉侵人椎管矣2 mm外，其他螺钉均位于椎弓根骨皮质内。寰椎左右侧预设最佳钉道内倾角度分别为9.4。± 1.8。、9.8。± 1.6。，实际钉道内倾角度分别为8.7。± 1.6。、10.6。±2.2。；左右侧预设最佳钉道头倾角度分别为8.9。±2.5。、8.8。±2.3。，实际钉道头倾角度分别为9.3。±2.9。、9.4。±3.5。〇枢椎左右侧预设最佳钉道内倾角度分别为21.9。±6.6。、22.4。±6.9。，左右侧实际钉道内倾角度分别为24.1。± 6.3。、20.8。± 6.4。；左右侧预设最佳钉道头倾角度分别为23.7。± 7.3。、24.2。± 7.2。，左右侧实际钉道头倾角度分别为22.1° ± 7.9°、22.3° ± 7.6°。寰枢椎术后实际钉道与术前预设最佳钉道的内倾角、头倾角、进钉点坐标差异均无统计学意义（P > 〇.〇5 )。结论标杆型3D打印导板辅助寰枢椎椎弓根置钉方向可调整性好，置钉准确度较高，为临床寰枢椎置钉提供了一种新的方法。

Objective To investigate the feasibility of establishing a 3D printed navigational template for atlantoaxialpedicle screw placement, and assess the accuracy of pedicle screw placement. Methods From June 2014 to August 2015,clinical data of 21 cases with atlantoaxial dislocation were analyzed. There were 12 males and 9 females with a mean age of42.6 ( range, 12-54 ) years old. Preoperatively, 3D printed navigational template with 2 guide rods was designed for everypatient using the Mimics 17.0 and 3-Matic 9.0 software. The 3D printed navigational template with 2 guide rods was used foratlantoaxial pedicle screw placement during operation. Postoperatively, all the patients took CT scan of cervical vertebrae.In the Mimics 17.0 software, pre- and post-operative trajactories and entry points of pedicle screws were measured aftermatching the positions of preoperative and postoperative 3D atlantoaxial models in a redefining coordinate. Results Allthe 21 patients underwent the surgeries successfully, with operation time of ( 193 ± 51 ) min and blood loss of ( 384 土127 ) mL. In total, 30 pedicle screws were placed for the atlas, and 42 for axis. There were 2 screws for atlas protruded intothe spinal canal within 2 mm. Transverse angle of ideal screw trajectories for atlantal pedicle screws measured 9.40 ± 1.80on the left and 9.8° ± 1.6° on the right, and actual screw trajectories measured 8.7° ± 1.6° and 10.6° ± 2.2°, respectively. Sagittal angle of ideal screw trajectories for atlantal pedicle screws measured 8.90 ± 2.50 on the left and 8.80 ± 2.30 on the right, andactual screw trajectories measured 9会30 ± 2.90 and 9.40 ± 3.50, respectively. Transverse angle of ideal screw trajectories for axialpedicle screws measured 21.90 ± 6.60 on the left and 22.40 ± 6.90 on the right, and actual screw trajectories measured 24.10 土6会3〇 and 20.8〇 ± 6.4〇, respectively. Sagittal angle of ideal screw trajectories for axial pedicle screws measured ± 7.3〇 onthe left and 24.2° ± 7.20 on the right, and actual screw trajectories measured 22.1° ± 7.9° and 22.30 ± 7.60, respectively. Therewere no statistically significant differences in the deviation of either screw orientation or entry point location between ideal andactual screw trajectories ( P > 0.05 ). Conclusion Using this 3D printed navigational template for atlantoaxial pedicle screwplacement, surgeons could change screw direction based on the template, and provide a high accuracy of screw placement.