术中即时三维导航辅助下后路内固定治疗症状型游离齿突

Posterior internal fixation of symptomatic os odontoideum aided by intraoperative three-dimensional fluoroscopy navigation

背景：上颈椎解剖变异较大且有重要的神经血管毗邻,对症状型游离齿突患者的手术治疗提出了挑战,目前有多种治疗方法,但各有局限。目的：评估术中即时三维导航辅助下行后路螺钉固定治疗症状型游离齿突患者的准确性和临床效果。方法：34例症状型游离齿突患者均在术中即时三维导航辅助下行后路内固定手术,采用寰枢椎经关节螺钉固定术21例,寰枢椎多轴螺钉固定术12例,另1例患者左侧为多轴螺钉固定右侧为经关节螺钉固定。颈部疼痛采用视觉模拟疼痛评分（VAS）,神经功能评价采用JOA评分,患者满意度采用Odom评分。将螺钉位置分为3级：Ⅰ级为理想置钉,螺钉完全位于骨皮质内;Ⅱ级为可接受置钉,螺钉穿出周围骨皮质但穿出部分小于螺钉直径的1/2;Ⅲ级为不可接受置钉,明显侵犯横突孔或是椎管。结果：全部患者获得随访,随访时间为6~65个月,平均25.7个月。34例患者共置入经关节螺钉43枚,多轴螺钉50枚。其中3枚多轴螺钉和4枚经关节螺钉轻度穿破单侧横突孔,但术中无椎动脉和脊髓损伤表现。患者的术前JOA评分为5~14分,平均8.3分,提高至末次随访的8~17分,平均12.4分,改善率为47.1%。术前VAS为3~7分,平均4.1分,降低至术后3个月随访的0~4分,平均0.7分,改善率为83.7%。末次随访的Odom评分：优为47%,良为38%,可为12%,差为3%。所有病例均获得复位和骨性融合,未出现内固定失效的并发症。结论：对于症状型游离齿突患者,术中即时三维导航辅助下后路螺钉内固定是一种安全、准确和有效的治疗方法。

Background： High anatomic variability of the upper cervical spine and its surrounding neurovascular structures has brought great challenges to the surgical treatment of symptomatic os odontoideum. Though a number of therapeutic methods are available now, each of them has their own limitations. Objective： To evaluate the accuracy and clinical effects of posterior screw fixation of symptomatic os odontoideum aided by intraoperative three-dimensional fluoroscopy navigation （ITFN）. Methods： Thirty-four patients with symptomatic os odontoideum received the ITFN-aided posterior internal fixation, 21 of them received the atlanto-axial transarticular screw fixation, 12 of them received the atlanto-axial polyaxial screw fixation, and 1 patient received the polyaxial screws fixation on the left side and transarticular screw fixation on the right side. Cervical pain was measured by the visual analogue scale （VAS） scores, nerve functions were evaluated by JOA （Japanese Orthopaedic Association） scale, and the patients＇ satisfaction was accessed by Odom＇s criteria. The position of the screw was graded into 3 levels. Level I, the screw was at the ideal position, i.e. the screw was completely located within the bone cortex; level II, the screw had an acceptable position, i.e. less than half of the diameter of the screw entered into the surrounding cortex; level III, the screw was located at an unacceptable position, i.e. the screw clearly invaded into the transverse foramen or spinal canal. Results： All patients were followed up, and the mean follow-up period was 25.7 （6-65） months. Forty-three transarticular screws and 50 polyaxial screws were placed in the 43 patients in total, among which 3 polyaxial screws and 4 transarticular screws slightly penetrated into the transverse foramen unilaterally but no injury was caused to the vertebral artery or the spi- nal cord. The average JOA score was 8.3 （5-14） points before the surgery and was increased to 12.4 （8-17） points at the last follow-up, the improvement rate was 47. i%. The average VAS score was 4.1 （3-7） points before the surgery and was im-proved to 0.7 （0-4） points 3 months after the surgery, the improvement rate was 83.7%. According to Odom＇s criteria, out- comes at the last follow-up were as follows： 47% were excellent, 38% were good, 12% were fair, and 3% were poor. Resto- ration and bony fusion were achieved in all patients; there was no failure of internal fixation. Conclusions： Posterior internal fixation aided by ITFN is a safe, accurate, and effective treatment for patients with symptom- atic os odontoideum.