3D打印的颈椎侧块螺钉导向板辅助侧块螺钉置钉的评估

Three-dimensional printing of cervical lateral mass screw guide plate assisted lateral mass screw placement

目的 评估分析与徒手置钉相比,运用3D打印的个体化置钉导向板是否可以增加下颈椎侧块螺钉的置钉准确性。方法 前瞻性收集2018年1~6月首都医科大学附属北京友谊医院收治的行颈椎4~6侧块螺钉内固定的患者12例,利用随机数字表将患者随机分为徒手置钉组(A组)和3D打印导板置钉组(B组),每组各6例。A组采用传统徒手置入侧块螺钉,B组患者术前行颈椎薄扫CT检查,将影像学资料输入MIMICS软件,生成颈椎3D模型,在模型上设计出理想的个体化置钉入点、角度和深度。以此数据运用3D打印机制备个体化颈椎侧块螺钉置钉导向板。术中A组采用徒手置钉,B组采用3D打印导向板辅助置钉。所有患者术后均行颈椎CT扫描。通过CT平扫+重建记录每枚螺钉入点、置钉轨迹、冠状位外倾角(α角)、矢状位头倾角(β角)等。通过各个螺钉置入角度、轨迹和并发症情况对螺钉进行评分和分级。结果 A组和B组患者间年龄[(63.50±4.04)岁vs.(56.33±10.78)岁]、手术时间[(161.25±16.52)min vs.(171.67±19.41)min]、出血量[(375.00±50.00)ml vs.(300.00±89.44)ml]差异均无统计学意义( P >0.05)。两组间临床症状缓解率差异亦无统计学意义[(48.45±5.91)% vs.(50.45±6.01)%]。在螺钉置入角度上,α角A组平均(21.88±2.88)°,B组平均(23.69±2.36)°,两组间差异具有统计学意义( t =-2.675, P =0.001),特别是在门轴侧螺钉差异更加显著[(21.25±3.11)° vs.(24.55±1.34)°, t =-4.014, P =0.000)]。β角两组间差异无统计学意义[(23.33±4.08)° vs.(24.39±2.14)°, t =-1.308, P =0.196]。根据我们制定的螺钉分级评分系统,A组螺钉评级得分(6.08±1.56)分,而B组平均(7.56±0.91)分,两者间差异具有统计学意义( t =-4.622, P =0.000)。A组螺钉优良率也显著低于B组(55.56% vs. 94.44%)。所有患者均无内固定相关并发症发生。结论 运用3D打印的个体化置钉导向板辅助进行颈椎侧块螺钉置钉,方法简单有效,可以显著提高置钉的准确性和优良率。3D打印导向板辅助置钉螺钉置入轨迹优于徒手置钉,特别是在门轴侧螺钉置入时优势更加明显。

Objective To evaluate whether using 3D printing patient-specific guide template could increase the accuracy and safety of lateral mass screws insertion in the subaxial cervical spine comparing with free hand. Methods A prospective randomized controlled cohort study was performed. 12 patients were enrolled in Beijing Friendship Hospital, Capital Medical University between January to June in 2018. All patients undergone expansive open-door laminoplasty with bilateral C4-6 lateral mass screws fixation and fusion. They were divided into two groups according to the random number table: Group A (6 cases) is screw insertion by free-hand and group B (6 cases) is screw insertion by 3D printing patient-specific guide template. In group B, a 3D model of cervical spine based on preoperative CT scanning data was built and the trajectories of the screws was digital designed in MIMICS software. Then according to these data, the patient-specific plastic template was manufactured by 3D printer, which guide the drill and insertion of screws. All patients underwent routine cervical spine CT scan after operation. The entrance point, trajectories, inclination angle in coronal position (angle α) and in sagittal position (angle β)were recorded. Each screw was graded and scored according to the screw' position and trajectories. Independent t-test and chi-square test were performed for statistical analysis. Results There was no significant difference between these two groups in patient's mean age (63.50±4.04) years vs.(56.33±10.78) years, mean operative time (161.25±16.52) min vs.(171.67±19.41) min, mean bleeding (375.00±50.00) ml vs.(300.00±89.44) ml ( P >0.05). In the aspect of screw trajectories, the mean angle α(inclination angle in coronal position) was (21.88±2.88)° in group A and (23.69±2.36)° in group B. There was a significant difference between these two groups ( t =-2.675, P =0.001), especially for the screws at the door hinge side (21.25±3.11)° vs.(24.55±1.34)°, t =-4.014, P =0.000). The mean angle β(inclination angle in sagittal position) was (23.33±4.08)° in group A and (24.39±2.14)° in group B, while there was no significant difference between them ( t =-1.308, P =0.196). The mean score of all screws was (6.08±1.56) scores in group A and (7.56±0.91) scores in group B. The difference between these two groups was significant ( t =-4.622, P =0.000). The grade of excellent and good was 55.56% in group A and 94.44% in group B. There was no severe screw related complications in both two group. Conclusion Lateral mass screw insertion guiding by 3D printing patient-specific template was accurate and simple, with few screw related complications. Using this kind of guide template, the trajectories of screws were better than free-hand, especially at the door hinge side.