Shen Kai, Deng Zhongliang, Yang Junsong, Liu Chao, Zhang Ranxi
Department of Orthopedics, The Second Affiliated Hospital, Chongqing Medical University, No. 76 Linjiang Road, Yuzhong District, Chongqing, 400010, People's Republic of China.
Department of Orthopedics, Chongqing General Hospital, No. 312 Zhongshan Road, Yuzhong District, Chongqing, 400013, People's Republic of China.
Arch Orthop Trauma Surg. 2017 Oct;137(10):1349-1355. doi: 10.1007/s00402-017-2781-0. Epub 2017 Aug 29.
Current surgical methods to treat atlantoaxial instability pose potential risks to the surrounding blood vessels and nerves of operative approach. Therefore, more secure and highly effective methods are expected. This study sought to assess the biomechanical efficacy of a novel unilateral double screw-rod fixation system by comparing with traditional and emerging fixation methods in cadaveric models.
Ligamentous cervical spines (C0-C7) from ten fresh cadaveric specimens were used to complete range of motion (ROM) test in their intact condition (control group), destabilization, and stabilization after different fixations, including unilateral C1-C2 pedicle screws (PS) with a screw-rod system (Group A), bilateral C1-C2 PS with screw-rod systems (Group B), unilateral C1 posterior arch screws (PAS) and C2 laminar screws (LS) combined with an ipsilateral paralleled C1-C2 PS-rod (Group C), and unilateral C1 PAS and C2 LS combined with an ipsilateral crossed C1-C2 PS-rod (Group D). After that, pullout strength test was performed between PS and PAS using ten isolated atlas vertebras.
All fixation groups reduced flexibility in all directions compared with both control group and destabilization group. Furthermore, comparisons among different fixation groups showed that bilateral C1-C2 PS-rod (Group B), unilateral C1 PAS + C2 LS combined with an ipsilateral paralleled C1-C2 PS-rod (Group C) and unilateral C1 PAS + C2 LS combined with an ipsilateral crossed C1-C2 PS-rod (Group D) could provide a better stability, respectively, in all directions than unilateral C1-C2 PS-rod (Group A). However, no statistical significance was observed among Groups B, C, and D. Data from pullout strength test showed that both C1 PS (585 ± 53 N) and PAS (463 ± 49 N) could provide high fixed strength, although PS was better (P = 0.009).
The surgical technique of unilateral C1 PAS + C2 LS combined with a ipsilateral crossed C1-C2 PS-rod fixation could provide a better stability than the traditional unilateral PS-rod fixation and a same stability as bilateral PS-rod fixation, but with less risk of neurovascular injury. Therefore, this new technique may provide novel insight for an alternative of atlantoaxial instability treatment.
目前治疗寰枢椎不稳的手术方法对手术入路周围的血管和神经存在潜在风险。因此，人们期待更安全、高效的方法。本研究旨在通过在尸体模型中与传统和新型固定方法进行比较，评估一种新型单侧双螺杆固定系统的生物力学疗效。
使用来自10个新鲜尸体标本的颈椎韧带结构（C0-C7）在完整状态（对照组）、失稳状态以及不同固定后的稳定状态下完成活动度（ROM）测试，这些固定方法包括单侧C1-C2椎弓根螺钉（PS）加螺杆系统（A组）、双侧C1-C2 PS加螺杆系统（B组）、单侧C1后弓螺钉（PAS）和C2椎板螺钉（LS）联合同侧平行的C1-C2 PS-杆（C组）以及单侧C1 PAS和C2 LS联合同侧交叉的C1-C2 PS-杆（D组）。之后，使用10个分离的寰椎进行PS和PAS之间的拔出强度测试。
与对照组和失稳组相比，所有固定组在各个方向上的灵活性均降低。此外，不同固定组之间的比较表明，双侧C1-C2 PS-杆（B组）、单侧C1 PAS + C2 LS联合同侧平行的C1-C2 PS-杆（C组）和单侧C1 PAS + C2 LS联合同侧交叉的C1-C2 PS-杆（D组）在各个方向上分别比单侧C1-C2 PS-杆（A组）能提供更好的稳定性。然而，B、C和D组之间未观察到统计学差异。拔出强度测试数据表明，C1 PS（585 ± 53 N）和PAS（463 ± 49 N）均能提供较高的固定强度，尽管PS更好（P = 0.009）。
单侧C1 PAS + C2 LS联合同侧交叉的C1-C2 PS-杆固定的手术技术比传统的单侧PS-杆固定能提供更好的稳定性，与双侧PS-杆固定具有相同的稳定性，但神经血管损伤风险更小。因此，这项新技术可能为寰枢椎不稳的治疗提供新的选择思路。
