3D打印技术辅助经口前路个性化手术治疗复杂颅颈交界区畸形

Individualized transoral anterior surgery for complex craniocervical junction disorder with assistance of 3D printing technology

目的探讨3D打印技术在复杂颅颈交界区畸形经口咽前路个性化手术中的应用价值。方法回顾性分析2009年12月-2013年12月利用3D打印技术辅助治疗的48例颅颈交界区复杂畸形的寰枢椎脱位患者。男19例，女29例；年龄6～59岁，平均35岁。其中合并寰椎枕骨化28例，游离齿状突19例，合并C2-3融合17例，合并2-5融合1例，寰椎后弓不连1例，寰椎后弓缺如1例。所有患者均有肢体麻木、四肢无力、站立或行走不稳等脊髓压迫症状。颈椎MRI检查均发现寰齿间隙（ADI）增宽，寰枢椎脱位。术前将CT扫描获得的原始DICOM格式图像数据转入Simpleware软件，进行三维图像建模，然后以STL格式输入3D打印机复制出与患者等比例的颈椎快速成型模型供手术使用。患者均实施经口咽前路复位钢板（TARP）固定手术，其中1例接受前后路联合手术。测量术前、术后患者ADI以判断寰枢椎复位情况，测量颈延角（CMA）以评价脊髓压迫改善情况。采用日本骨科学会（JOA）评分判断患者脊髓功能改善情况。结果手术均顺利，手术时间（145±45）min，出血量（53±15）ml。手术共置入寰椎侧块螺钉96枚，逆向枢椎椎弓根螺钉62枚，枢椎椎体螺钉36枚，枢椎后路椎弓根螺钉1枚，枢椎椎板螺钉1枚。术后CT扫描结果显示，62枚逆向枢椎椎弓根螺钉有4枚外倾角偏大，部分进入椎动脉孔，但未出现临床症状；36枚枢椎椎体螺钉均位于椎体内。置钉总优良率98％。术后CT重建图像显示，寰枢椎较术前明显复位，ADI由术前（8．7±4．9）IBm改善为术后（2．7±1．9）mm（P〈0．05），CMA由术前（123±17）。改善为术后（159±18）°（P〈0．05）。术后患者肢体麻木、肌肉无力等症状均较术前有明显改善。术前JOA评分为（9．5±1．7）分，术后3个月复查恢复至（15．7±0．9）分（P〈0．05）。术后随访10-58个月，患者均获骨性愈合。结论对于合并颅颈交界畸形的寰枢椎脱位患者，3D打印技术有助于对手术方案的设计、手术过程的辅助，起到提高手术精准度及安全性的作用。

Objective To evaluate the value of 3D priming technology in transoral anterior surgery for complex craniocervical junction disorder. Methods From December 2009 to December 2013, 48 cases of atlantoaxial dislocation associated with complex craniocervical malformation were operated with the assistance of 3D printing technology. There were 19 males and 29 females, with mean 35 years of age （ range, 6 to 59 years）. Preoperative complications included 28 cases of atlas assimilation, 19 cases of os odontoideum, 17 cases of C2-3 fusion, 1 case of C2-5 fusion, 1 case of C1 posterior arch disconnection, and 1 case of C1 posterior arch aplasia. All cases had symptoms of spinal compression such as numbness and weakness of the extremity, standing or walking unsteady, etc. Preopoerative cervical MRI examinations showed the enlargement of anterior atlas-dens interval （ADI） or atlantoaxial dislocation. All cases＇ CT data in Dicom form were input into the Simpleware software to reconstruct 3D image, and then the image in STL form was imported to the 3D printer to make a fast prototyping model for the operation with same size as the cases＇ cervical spine. Based on above works, all cases underwent transoral anterior reduction plate （TARP） fixation in the craniocervical junction zone, including combined anterior-posterior surgery in 1 case. ADI was measured to evaluate the reduction of atlantoaxial dislocation, cervical-medullary angle （CMA） was measured to evaluate the improvement of compression on the medulla, and Japanese Orthopedic Association （JOA） scoring system was used to evaluate the improvement of spinal function. Results All cases went through successful surgery. Mean operation time was （ 145 ± 45 ） min and mean blood loss was （53 ±15）ml. A total of 96 atlas lateral mass screws, 62 reverse axis pedicle screws and 36 axis vertebral body screws, 1 posterior axis pedicle screw and 1 axis translaminar screw were used. Postoperative CT scans showed all screw trajectories were good except that 4 reverse axis pedicle screws violated into the vertebrae artery foramen due to large outward inclination angle. No neurologic defect was found in all cases. Excellent rate of screw placement was 98%. Postoperative CT reconstruction images showed significant atlantoaxial reduction. ADI improved from （8.7 ± 4.9） mm preoperatively to （2.7 ± 1.9） mm postoperatively （ P 〈 0.05 ）. CMA changed from preoperative （ 123 ± 17 ）° to postoperative （ 159 ± 18 ） ° （ P 〈 0.05 ）. All cases had obvious improvement of spinal compression symptoms. JOA scores improved from （9.5 ± 1.7）points preoperatively to （15.7 ＋0.9）points at 3 months postoperatively （P 〈0.05）. All cases achieved bone union at a follow-up of 10-58 months. Conclusion 313 printing technology is helpful to the operation plan and manipulation for atlantoaxial dislocation associated with complex craniocervical deformities, which may improve the accuracy and safety during the procedure.