Guo-Xin Jin, Huan Wang
Department of Orthopaedic Surgery, Shengjing Hospital, China Medical University, Shenyang City, Liaoning Province, China.
J Neurosurg Spine. 2016 Feb;24(2):315-320. doi: 10.3171/2015.4.SPINE14517. Epub 2015 Oct 30.
OBJECT Atlantoaxial instability often requires surgery, and the current methods for fixation pose some risk to vascular and neurological tissues. Thus, new effective and safer methods are needed for salvage operations. This study sought to assess unilateral C-1 posterior arch screws (PASs) and C-2 laminar screws (LSs) combined with 1-side C1-2 pedicle screws (PSs) for posterior C1-2 fixation using biomechanical testing with bilateral C1-2 PSs in a cadaveric model. METHODS Six fresh ligamentous human cervical spines were evaluated for their biomechanics. The cadaveric specimens were tested in their intact condition, stabilization after injury, and after injury at 1.5 Nm of pure moment in 6 directions. The 3 groups tested were bilateral C1-2 PSs (Group A); left side C1-2 PSs with an ipsilateral C-1 PAS + C-2 laminar screw (Group B); and left side C1-2 PSs with a contralateral C-1 PAS + C-2 LS (Group C). During the testing, angular motion was measured using a motion capture platform. Data were recorded, and statistical analyses were performed. RESULTS Biomechanical testing showed that there was no significant difference among the stabilities of these fixation systems in flexion-extension and rotation control. In left lateral bending, the bilateral C1-2 PS group decreased flexibility by 71.9% compared with the intact condition, the unilateral C1-2 PS and ipsilateral PAS+LS group decreased flexibility by 77.6%, and the unilateral C1-2 PS and contralateral PAS+LS group by 70.0%. Each method significantly decreased C1-2 movements in right lateral bending compared with the intact condition, and the bilateral C1-2 PS system was more stable than the C1-2 PS and contralateral PAS+LS system (p = 0.036). CONCLUSIONS A unilateral C-1 PAS + C-2 LS combined with 1-side C-1 PSs provided the same acute stability as the PS, and no statistically significant difference in acute stability was found between the 2 screw techniques. These methods may constitute an alternative method for posterior atlantoaxial fixation.
寰枢椎不稳常需手术治疗，而目前的固定方法对血管和神经组织存在一定风险。因此，挽救手术需要新的有效且更安全的方法。本研究旨在通过在尸体模型中对双侧C1-2椎弓根螺钉（PSs）进行生物力学测试，评估单侧C-1后弓螺钉（PASs）和C-2椎板螺钉（LSs）联合单侧C1-2椎弓根螺钉用于C1-2后路固定的效果。方法：对6具新鲜的保留韧带的人体颈椎进行生物力学评估。尸体标本在完整状态、损伤后固定以及损伤后在6个方向施加1.5 Nm纯力矩的情况下进行测试。测试的3组分别为双侧C1-2椎弓根螺钉（A组）；左侧C1-2椎弓根螺钉联合同侧C-1后弓螺钉 + C-2椎板螺钉（B组）；左侧C1-2椎弓根螺钉联合对侧C-1后弓螺钉 + C-2椎板螺钉（C组）。在测试过程中，使用运动捕捉平台测量角运动。记录数据并进行统计分析。结果：生物力学测试表明，这些固定系统在屈伸和旋转控制方面的稳定性无显著差异。在左侧侧弯时，双侧C1-2椎弓根螺钉组与完整状态相比灵活性降低了71.9%，单侧C1-2椎弓根螺钉联合同侧后弓螺钉 + 椎板螺钉组灵活性降低了77.6%，单侧C1-2椎弓根螺钉联合对侧后弓螺钉 + 椎板螺钉组降低了70.0%。与完整状态相比，每种方法在右侧侧弯时均显著降低了C1-2的运动，且双侧C1-2椎弓根螺钉系统比C1-2椎弓根螺钉联合对侧后弓螺钉 + 椎板螺钉系统更稳定（p = 0.036）。结论：单侧C-1后弓螺钉 + C-2椎板螺钉联合单侧C-1椎弓根螺钉提供了与椎弓根螺钉相同的即刻稳定性，两种螺钉技术在即刻稳定性方面未发现统计学显著差异。这些方法可能构成寰枢椎后路固定的一种替代方法。
