3D打印导板在寰枢椎后路椎弓根螺钉固定术中的临床应用

目的 探讨3D打印导板技术辅助寰枢椎后路椎弓根螺钉固定术治疗寰枢椎骨折脱位的可行性及临床疗效。方法 回顾性分析2015年1月—2017年6月长沙医学院附属石门医院,采用3D打印导板技术辅助寰枢椎后路椎弓根螺钉内固定术治疗的11例寰枢椎骨折脱位患者的临床资料。其中男9例、女2例,年龄52～69岁。寰椎骨折4例,其中前弓骨折2例、前后弓骨折2例;枢椎骨折5例,其中ⅡC型齿状突骨折4例、Hangman骨折1例;寰枢关节脱位2例。术前将患者颈椎CT扫描断层Dicom数据导入逆向工程软件Mimics 17.0,对目标椎体进行分割重建,选取目标椎体后方结构表面形态蒙版扩张,采用布尔运算获得导板模型,分别使用聚乳酸高分子材料和光敏树脂材料3D打印快速成型制作寰枢椎骨折脱位模型以及导板模型。术前利用聚乳酸高分子材料打印的寰枢椎骨折脱位模型进行模拟手术操作,确认导板设计的准确性。光敏树脂材料导板采用环氧乙烷消毒后封装以备术中使用。手术采用常规颈椎后入路切口,术中充分暴露椎体后方表面结构形态,根据术前模拟操作,利用导板辅助置入寰枢椎椎弓根螺钉。记录患者手术时间、术中出血量以及并发症的发生情况。术后6个月根据CT扫描判断螺钉与椎弓根位置关系,采用Kawaguchi等方法评价螺钉置入质量;术后1年采用VAS评估患者颈肩部疼痛情况,采用JOA评分评价患者颈髓神经功能情况。结果 11例患者均顺利完成手术,手术时间(130.55±18.83)min;术中出血量(266.36±72.43)mL。11例患者共置入44枚椎弓根螺钉,术后6个月采用Kawaguchi等级评价标准评价螺钉置入质量:0级41枚(93.18%),1级2枚(4.55%),2级1枚(2.27%)。所有患者获随访,随访时间12～26个月,平均17.18个月。随访期间无切口感染、脑脊液漏等并发症出现。术后1年患者颈肩部疼痛VAS(1.00±0.77)分,明显低于术前的(7.91±1.04)分;颈髓神经功能JOA评分(13.45±1.69)分,明显高于术前的(8.18±1.17)分:差异均有统计学意义(t=3.020、14.685,P值均＜0.05)。结论 3D打印导板技术辅助寰枢椎后路椎弓根螺钉固定术治疗寰枢椎骨折脱位,可降低寰枢椎椎弓根螺钉置入的手术难度,提高置钉精准度,安全有效,可获得良好的近期临床疗效。

Clinical application of 3D-printed navigation template in posterior atlantoaxial pedicle screw fixation

Objective To discuss the feasibility and clinical efficacy of 3D-printing navigation template for posterior atlantoaxial pedicle screw fixation for the treatment of atlantoaxial fracture and dislocation.Methods From January 2015 to June 2017, 11 patients receiving posterior internal fixation with atlantoaxial pedicle screw placement assisted by the 3D-printed navigation template at Affiliated Shimen Hospital of Changsha Medical University were recruited, and their clinical data were reviewed. There were 9 males and 2 females, who were aged from 52 to 60 years old. Four cases had fracture of atlas, with 2 cases in the anterior arch and 2 cases in both anterior and posterior arches. Five cases had atlantoaxial fracture, with 4 cases of type ⅡC odontoid process fracture and 1 case of Hangman's fracture. Two cases had dislocation of the atlantoaxial joint. Dicom images from preoperative cervical CT scan were imported into the reverse engineering software. Segmentation and reconstruction of the target vertebral body were performed. Mask expansion was conducted for the surface morphology of the posterior structure of the target vertebral body. Boolean operation was implemented to obtain the navigation template. Polylactic acid(PLA) and photosensitive resin were used for 3D-printing and rapid prototyping of atlantoaxial fracture and dislocation model and navigation template model, respectively. The surgery was first simulated using the 3D-printed PLA of atlantoaxial fracture and dislocation model, so as to conform the accuracy of navigation template design. The photosensitive resin was disinfected with ethylene oxide and encapsulated prior to use. A conventional posterior cervical approach was adopted. The surface morphology of the posterior vertebra was fully exposed during operation and the atlantoaxial pedicle screw was placed with the assistance of 3D-printed navigation template according to preoperative simulation. The surgical time, intraoperative blood loss and incidence of complications were recorded. The position relationship of the pedicle screw and pedicle of vertebral arch was determined by CT scan at 6 months after surgery. The quality of pedicle screw placement was assessed by using Kawaguchi's method. The neck and shoulder pain were assessed by using the VAS score at 1 year after surgery. The function of the cervical nerve was assessed by JOA score.Results The operation was successfully performed for all 11 patients. The average surgical time was (130.55±18.83) min, and the average intraoperative blood loss was (266.36±72.43) mL. A total of 44 pedicle screws were placed in 11 patients. Using Kawaguchi's grading system, 93.18%(41/44) of pedicle screw were of grade 0, 4.55%(2/44) of pedicle screw were of grade 1 and 2.27%(1/44) of pedicle screw were of grade 2. All patients were followed up for an average of 17.18 months (12 to 26 months). No postoperative complications, such as incision infection and cerebrospinal fluid leak, occurred during the follow-up. The average VAS score at 1 year after surgery (1.00±0.77) was significantly improved as compared with that before surgery (7.91±1.04). The average JOA score characterizing the function of cervical nerve at 1 year after surgery (13.45±1.69) was also significantly improved as compared with that before surgery (8.18±1.17), there were statistical differences (t=3.020 and 14.685, all P values＜0.05).Conclusions Posterior atlantoaxial pedicle screw fixation with the assistance of 3D-printed navigation template for the treatment of atlantoaxial fracture and dislocation can reduce the difficulty of pedicle screw placement while improve the accuracy of such placement. It is a safe and effective method and which can achieve a good short-term efficacy. This technology is worthy of popularization.