WANG Chao, WANG Sheng-lin, YAN Ming
Department of Orthopaedics, Third Hospital of Peking University, Beijing 100083, China.
Zhonghua Wai Ke Za Zhi. 2008 Oct 15;46(20):1557-61.
C(2) pedicle screw is the classic instrumentation for posterior C(2) fixation. But it could be dangerous in case of anatomical variation, such as high riding vertebral artery and small C(2) pedicle. C(2) trans-laminar screw could be an alternative choice. This retrospective study is to evaluate the feasibility of C(2) trans-laminar screw for atlantoaxial instability with anatomical variation.
In our clinical work, we had nine atlantoaxial instability cases with C(2) pedicle malformation. If the malformation is unilateral, we inserted one C(2) trans-laminar screw and one C(2) pedicle screw in the normal pedicle; if the malformation is bilateral, bilateral trans-laminar screws were used. Then C(2) instrumentation could be connected with C(1) lateral mass screw or occipital screw in cases with C(1) occipitalization. Then atlantoaxial or occipitocervical fusion could be done with morselized autogenous cancellous iliac grafts.
Nine cases had C(2) trans-laminar screw, including 2 atlantoaxial fusion and 7 occipitocervical fusion. Six cases had unilateral trans-laminar screw and 3 had bilateral trans-laminar screw. Radiographs demonstrated all the screws were placed satisfactorily except one. There was no neurological deterioration or vertebral artery injury. All the cases had an average follow-up of 9 months (4 - 13 months). All patients attained solid fusion without screw failure. In the 8 cases with neurological deficit, 3 were excellent, 1 was good, 2 were fair and 2 had no change.
C(2) trans-laminar screw fixation could provide sufficient stability. This technique could be an alternative to standard C(2) pedicle screw in cases with pedicle malformation and high riding vertebral artery. It is safe and simple in experienced hands.
C2椎弓根螺钉是后路C2固定的经典器械。但在存在解剖变异的情况下，如椎动脉高位走行和C2椎弓根细小，使用该螺钉可能存在危险。C2经椎板螺钉可作为一种替代选择。本回顾性研究旨在评估C2经椎板螺钉治疗伴有解剖变异的寰枢椎不稳的可行性。
在我们的临床工作中，有9例寰枢椎不稳且C2椎弓根畸形的病例。若畸形为单侧，我们在正常椎弓根置入1枚C2经椎板螺钉和1枚C2椎弓根螺钉；若畸形为双侧，则使用双侧经椎板螺钉。然后，在存在C1枕化的病例中，C2器械可与C1侧块螺钉或枕骨螺钉相连。接着，使用颗粒状自体髂骨松质骨移植进行寰枢椎或枕颈融合。
9例患者采用了C2经椎板螺钉，其中2例行寰枢椎融合，7例行枕颈融合。6例为单侧经椎板螺钉，3例为双侧经椎板螺钉。影像学检查显示，除1枚螺钉外，所有螺钉置入位置均满意。未发生神经功能恶化或椎动脉损伤。所有病例平均随访9个月（4 - 13个月）。所有患者均实现了牢固融合，无螺钉松动。在8例有神经功能缺损的患者中，3例恢复极佳，1例良好，2例尚可，2例无变化。
C2经椎板螺钉固定可提供足够的稳定性。在椎弓根畸形和椎动脉高位走行的病例中，该技术可替代标准的C2椎弓根螺钉。在经验丰富的医生操作下，它安全且简便。
