寰枢椎后路经关节螺钉固定术

目的评价参照枢椎椎管内壁行寰枢椎后路经关节螺钉固定（Naged技术）的可行性。方法2002年1月～2005年1月，对31例寰枢椎不稳患者行后路经关节螺钉内固定术，男18例，女13例；平均年龄36．8岁。螺钉置入方法：紧贴枢椎椎管内壁确定距离中线的距离，以枢椎椎板下缘上2帅为进针高度，两线交叉点即为螺钉进针点。螺钉平行矢状面，指向寰枢关节面后缘高度，通过C型臂机侧位像确认螺钉向上倾斜角度。术后结合正、侧位x线片、螺旋CT三维重建及断层扫描图像，评价螺钉置入准确程度。根据螺钉与寰枢椎关节面的位置关系分为A、B、C三区，A区螺钉通过寰椎下关节面；B区螺钉在关节面的前方或后方（前方为B1，后方为B2）；C区为螺钉在关节面的内侧或外侧（内侧为C1，外侧为C2）。结果共置入60枚螺钉。术中无椎动脉、颈脊髓、颈神经根及颅神经损伤。所有患者获得6～18个月（平均9个月）的随访，植骨融合时间为3～12个月，平均5个月，颈脊髓及神经根症状改善明显者3例，部分改善者5例，无改善者1例，无神经症状加重患者。枕颈部疼痛完全缓解者8例，部分缓解者6例，无缓解者2例。60枚螺钉中，A区58枚（96．7％），B1区2枚（3．3％），无B2及C区螺钉。结论参照枢椎椎管壁行寰枢椎后路经关节螺钉固定是安全可靠的。

Posterior atlantoaxial transarticular screw fixation

Objective To determine the feasibility of inserting posterior atlantoaxial transarticular screws (Magerl screw technique) by referring to the spinal canal of axis (C2). Methods Between January 2002 and January 2005, 31 patients (18 males and 13 females; the mean age, 36. 8 years) with atlanto-axial instability were treated with Magerl technique by referring to the spinal canal of C2 (60 screws) . The starting point of the screw placement was identified at the crossing point of the vertical line closely along the spinal canal and the horizontal line 2 mm cephalad to the inferior edge of the lamina in C2. The screw was parallel to the sagittal plane and towards the posterior edge of the atlantoaxial facet joint. To evaluate the screw position, postoperative plain radiograms, three-dimensional and muti-planar reconstruction of spiral CT scans were obtained. Five areas were identified to determine the relationship between the atlantoaxial facet joint and the screw: area A (screw inside the facet joint), area B1 (screw anterior to the facet joint), area B2 (screw posterior to the facet joint), area C1 (screw in the spinal canal), and area C2 (screw in the foramen of vertebral artery). Results There were no injuries to vertebral artery, spinal cord, or cervical nerve root during surgery. The 31 cases had complete follow-up records and a mean follow-up period of 9 months (range, 6 to 18 months) . The bony fusion was averagely 5 months (range, 3 to 12 months) . The improvement in spinal cord function was marked in 3 cases, good in 5 cases, unchanged in 1 cases. No case got worse. The local pain relief was complete in 8 cases, good in 6 cases, poor in 2 cases. Of the 60 screws, 58 were in area A(96. 7% ), 2 in B1(3. 3% ), and none in area B2 and C. Conclusion The method of inserting posterior atlantoaxial transarticular screws by referring to the spinal canal of C2 is reliable.