Atlantoaxial transarticular screw fixation and posterior fusion using polyester cable: a 10-year experience

Purpose

To retrospective review the clinical outcomes of the modified operative technique using a polyester suture material (Ethibond* Excel) for atlantoaxial transarticular screw fixation and posterior fusion.

Methods

The retrospective reviews were conducted from 2002 to 2012. The patient’s medical record reviews included demographic data, cause of atlantoaxial instability, orthopedic and surgical history, clinical presentation, radiographic finding including plain radiography, complications, operative detail, and outcome of treatment. Fusion of C1–C2 was defined as either graft consolidation or absence of C1–C2 movement on lateral flexion–extension radiograph.

Results

Twenty-three patients demonstrated clinical and radiographic evidence of atlantoaxial instability (13 men and 10 women, with a mean age of 42 years). Majority of atlantoaxial instability was caused by trauma. Most common clinical symptom was neck pain with or without cervical myelopathy. Bilateral screws were placed in 18 of the 23 patients. Five patients underwent placement of unilateral screws. The 13 patients were inserted by screws with diameter 4.0 mm. The means screw length was 40.33 mm. The means of operative time and estimated blood loss were 3.6 h and 234 ml, respectively. The mean of follow-up duration was 18 months. All 41 screws were positioned satisfactorily in C1 lateral mass. All 23 patients achieved fusion (100 % fusion rate). After a period of follow-up, 9 of the 10 neurological deficit patients had completely recovered.

Conclusions

We concluded that the atlantoaxial transarticular screw fixation and posterior fusion using polyester cable can be used for C1–2 fusion with a high fusion rate and less complications in various cases.     

寰枢椎椎弓根螺钉固定技术在治疗寰枢椎不稳中的应用

目的 探讨寰枢椎椎弓根螺钉固定技术在寰枢椎不稳中的应用疗效.方法 2004年10月2008年12月,采用寰枢椎椎弓根螺钉固定技术治疗寰枢椎不稳12例,男7例,女5例,年龄26～62岁,平均49.4岁,其中枢椎齿状凸骨折5例,均为陈旧性AdersonⅡ型骨折;寰枢椎陈旧性脱位7例.所有患者均表现为枕颈区疼痛、颈部活动障碍.4例患者合并脊髓受压,Frankel分级C级和D级各2例.术前JOA评分5～12分,平均8.5分.术前均行颅骨牵引.寰椎进钉点在后结节中点旁18～20 mm与后弓下缘以上2 mm交点处,钉道方向与冠状面垂直,矢状面上头偏约5°,枢椎进钉点为下关节突内上象限,钉道方向内斜32°,上倾28°.结果 12例患者共植入寰、枢椎左右椎弓根螺钉各24枚,无一例发生脊髓或椎动脉损伤.所有患者均获成功随访,时间为6～48个月,平均25个月,术后6月JOA评分为13.5～16.7分,平均14.9分,改善率为87.4%.结论 寰枢椎椎弓根螺钉固定技术用于寰枢椎不稳的治疗中具有稳定固定的良好临床疗效.     

Atlantoaxial fusion using anterior transarticular screw fixation of C1–C2: technical innovation and biomechanical study

This study is an attempt to describe a new technique for anterior transarticular screw fixation of the atlantoaxial joints, and to compare the stability of this construct to posterior transarticular screw fixation with and without laminar cerclage wiring. Nine human cadaveric specimens were included in this study. The C1–C2 motion segment was instrumented using either anterior transarticular screws (group 1), posterior transarticular screws alone (group 2), or posterior screws with interlaminar cerclage wires (group 3). Using an unconstrained mechanical testing machine, the specimens were tested in rotation, lateral bending, and flexion-extension using nondestructive loads of ±2 N m. The specimens were also tested in translation using nondestructive loads of ±100 N. All values for the three groups with regards to anterior-posterior displacement, rotation, and lateral bending were similar as determined using a Kruskal–Wallis rank sum test with a significance level of p<0.05. The only significant difference was registered in flexion-extension where the cerclage wire added some strength to the construct. Anterior transarticular screw fixation of the atlantoaxial spine has several advantages over posterior fixation techniques, and is as stable as posterior transarticular fixation in all clinically significant planes of motion. The addition of posterior interlaminar cerclage wiring further improves resistance to flexion-extension forces. Anterior transarticular screw fixation of the atlantoaxial joint is a useful technique for achieving C1–C2 stabilization.     

The original hole-in-one guide for atlantoaxial transarticular screw fixation

Atlantoaxial fusion by transarticular screw fixation provides firm fixation, and good results have been reported. However, there are also problems, such as injury of the vertebral artery at the time of screw insertion. For accurate facet fusion, we developed a new hole-in-one guide for screw fixation and obtained good results with its use. In 60 adult subjects, we measured the antero-posterior and transverse axes and determined the center of the atlantoaxial surface and the insertion point of the screw in three dimensions on computed tomography scans. Based on these values, we measured the optimum screw insertion angle on sagittal and coronal planes, and the distance between the center and the posterior margin of the joint surface; our new hole-in-one guide was produced with these data. When the guide tip is determined to be located at the center posterior margin of the axial joint surface, and the guidewire insertion point is determined to be located at the center of the axial inferior facet immediately above the C2/3 joint, the guidewire is passed through the axial pedicle and the center of the atlantoaxial joint. Since April 1997, we have used this hole-in-one guide technique in eight patients with atlantoaxial instability. The screws passed the pars interarticularis and the center of the atlantoaxial joint in all patients with safety and accuracy. No complications associated with this technique occurred. Received: December 24, 1999 / Accepted: August 25, 2000     

微创前路经寰枢椎关节突固定融合治疗寰枢椎不稳

目的探讨微创前路经寰枢椎关节突固定融合治疗寰枢椎不稳的临床效果和并发症。方法 2007年5月-2010年12月,对13例寰枢椎不稳患者行前路经皮关节突螺钉固定和内镜下植骨。其中男11例,女2例;年龄17～61岁,平均41.3岁。受伤至手术时间5～14 d,平均7.4 d。合并横韧带断裂Jefferson骨折6例,齿状突骨折5例,游离齿状突2例。术前Frankel分级为D级2例,E级11例。记录手术时间、术中出血量、放射线暴露时间和并发症,术后X线片观察寰枢椎稳定性,末次随访时评价神经功能恢复情况,并行薄层CT扫描三维重建评价融合情况。结果手术时间95～156 min,平均124 min;术中出血量30～105 mL,平均65 mL;放射线暴露时间30～64 s,平均41 s。13例均获随访,随访时间12～47个月,平均25.9个月。无血管、脊髓神经、气管、食道损伤及内植物失败等并发症。植骨融合时间6个月,动力位X线片未见不稳。末次随访时Frankel分级均为E级。寰枢椎融合率为84.6%(11/13);2例关节间隙未见连续性骨桥形成,但寰枢椎稳定。结论微创前路经寰枢椎关节突固定融合是治疗寰枢椎不稳的一种安全有效方法,具有微创技术优点。     

Minimally invasive anterior transarticular screw fixation and microendoscopic bone graft for atlantoaxial instability

Purpose

Even though transarticular screw (TAS) fixation has been commonly used for posterior C1–C2 arthrodesis in both traumatic and non-traumatic lesions, anterior TAS fixation C1–2 is a less invasive technique as compared with posterior TAS which produces significant soft tissue injury, and there were few reports on percutaneous anterior TAS fixation and microendoscopic bone graft for atlantoaxial instability. The goals of our study were to describe and evaluate a new technique for anterior TAS fixation of the atlantoaxial joints for traumatic atlantoaxial instability by analyzing radiographic and clinical outcomes.

Methods

This was a retrospective study of seven consecutive patients with C1–C2 instability due to upper cervical injury treated by a minimally invasive procedure from May 2007 to August 2009. Bilateral anterior TAS were inserted by the percutaneous approach under Iso-C3D fluoroscopic control. The atlantoaxial joint space was prepared for morselized autogenous bone graft under microendoscopy. The data for analysis included time after the injuries, operating time, intraoperative blood loss, X-ray exposure time, clinical results, and complications. Radiographic evaluation included the assessment of atlantoaxial fusion rate and placement of TAS. Bone fusion of the atlantoaxial joints was assessed by flexion extension lateral radiographs and 1-mm thin-slice computed tomography images as radiographic results. Clinical assessment was done by analyzing the recovery state of clinical presentation from the preoperative period to the last follow-up and by evaluating complications.

Results

A total of 14 screws were placed correctly. The atlantoaxial solid fusion without screw failure was confirmed by CT scan in seven cases after a mean follow-up of 27.5 months (range 18–45 months). All patients with associated clinical presentation made a recovery without neurologic sequelae. Postoperative dysphagia occurred and disappeared in two cases within 5 days after surgery. There were no other complications during the follow-up period.

Conclusions

Percutaneous anterior TAS fixation and microendoscopic bone graft could be an option for achieving C1–C2 stabilization with several potential advantages such as less tissue trauma and better accuracy. Bilateral TAS fixation and morselized autograft affords effective fixation and solid fusion by a minimally invasive approach.     

记忆合金颈椎夹钩治疗寰枢椎不稳

目的评价自行研制的记忆合金颈椎后路夹钩治疗寰枢椎不稳的临床疗效并初步评价其安全性。方法8例寰枢椎不稳患者经颅骨牵引复位后,采用后路记忆合金颈椎夹钩内固定、寰枢椎融合术治疗,术后软颈围固定3个月。结果7例获随访,随访时间6~18个月。疗效评定采用NASCIS评分标准,优4例,良3例。术后无一例颈髓损伤加重及术后感染,7例均获骨性融合,无颈椎夹钩松脱、断裂发生。结论寰枢椎不稳采用记忆合金夹钩后路固定是一种简便易行、固定可靠、疗效优良的治疗方法。     

改良Magerl联合Gallie内固定治疗创伤性寰枢椎不稳

目的 探讨改良Magerl联合Oallie内固定治疗创伤性寰枢椎不稳的临床疗效并初步评价其安全性。方法 10例经颅骨牵引基本复位的创伤性寰枢椎不稳病例均实施改良Magei-l联合Gallie内固定、寰枢椎融合术，观察术后近期疗效及并发症情况。结果 平均随访14个月，1例出现椎一基动脉供血不足症状；一例单侧关节突螺钉未经过关节间隙，未出现不良并发症；4例脊髓损伤患者术后出现良好脊髓功能改善，术后无一例发生脊髓损伤加重及术后感染，全部病例均获得骨性融合，随访期间无内置物松动、脱落或断裂。结论 改良Magerl联合Gallie手术能起到良好的三点内固定效果，有利于上颈椎稳定性重建及脊髓损伤的恢复；只要手术操作正确、规范，术中C型臂X线机透视监测，严重并发症发生的可能性相当小。     

Computer-assisted Magerl's transarticular screw fixation for atlantoaxial subluxation

We report two patients with rheumatoid arthritis in whom posterior atlantoaxial fixation was carried out using transarticular screws with computer assistance. Two bilateral transarticular screws were inserted in one patient; however, in the other patient, only a unilateral screw was used, because computerized images showed that the vertebral artery at the other side was placed too medially to allow insertion of the screw. Neither of these patients had any neurovascular complications after surgery. Computer-assisted surgery is useful for avoiding neurovascular complications with transarticular screw fixation of C1-2. Received: January 26, 2001 / Accepted: August 13, 2001     

Virtual placement of posterior C1-C2 transarticular screw fixation

We wanted to evaluate how often safe and effective posterior C1-C2 transarticular screw placement is realizable when it is performed according to guidelines given in the literature. In 50 adult patients, computerized tomography scan data from C0 to C3 were transformed into a 3D spine model. Virtually, bilateral screws were placed from the medial third of the C2-C3 facet joint towards the rim of the C1 anterior arc parallel to midline. Three categories of virtual screw position were rated: optimal (virtual screw inside the C2 pars interarticularis, transversing the middle third of the atlantoaxial joint, and sparing the vertebral artery canal), suboptimal (virtual screw violating the C2 pars interarticularis, and/or transversing the lower or upper third of the C1-C2 joint, and sparing vertebral artery canal), and unacceptable (virtual screw breaching the vertebral artery canal). Optimal placement was seen in 74, suboptimal placement in 11, and unacceptable locations in 15 sites. We conclude that due to the variability of the anatomy of the upper cervical spine, optimal transarticular C1-C2 screw placement is not possible in up to 26%, and even hazardous in up to 15%. This paper was presented in part at the Jahrestagung der Deutschen Gesellschaft für Neurochirurgie, May 25–28, 2003, Saarbrücken, Germany