背景:C2峡部螺钉固定技术的出现在寰枢椎脱位或其他需要固定C2的情况下越来越受欢迎。然而,这种固定的生物力学稳定性知之甚少。
目的:比较和阐明C2椎弓根螺钉(C2PS)的生物力学稳定性,C2峡部螺钉(C2IS)和C2短峡部螺钉(C2SIS)固定技巧在寰枢关节脱位(AAD)中的应用。
方法:从健康的男性志愿者那里建立并验证了从枕骨到C3的三维有限元模型(FEM)。三个FEM,C1椎弓根螺钉(PS)-C2PS,C1PS-C2IS,还构建了C1PS-C2SIS。运动范围(ROM)和屈曲下的最大vonMises应力,扩展,横向弯曲和轴向旋转载荷进行了分析和比较。还评估了C2的三种固定的拔出强度。
结果:C1PS-C2IS模型显示,带屈曲的ROM减少最大,扩展,横向弯曲和轴向旋转。C1PS-C2PS模型在所有负载条件下均显示出与C2IS和C2SIS相比最小的ROM减少。C1PS-C2PS型号在所有方向上对螺钉的应力最大,其次是C1PS-C2SIS,最后是C1PS-C2IS。在轴向旋转和横向弯曲载荷下,这三个模型分别显示了螺钉上的最大和最小vonMises应力。三种模型的应力主要位于螺杆和杆的连接处。总的来说,C2PS的最大螺钉拔出强度,C2IS和C2SIS为729.41N,816.62N,分别为640.54N。
结论:在寰枢椎脱位患者中,C2IS固定提供了相当的稳定性,没有明显的应力集中。此外,与C2PS和C2SIS相比,C2IS具有足够的拔出强度。在AAD的情况下,C2峡部螺钉固定可能是生物力学上有利的选择。然而,未来的临床试验对于评估该技术的临床结果是必要的.
BACKGROUND: The emerging of the C2 isthmus screw fixation technique is gaining popularity in the setting of atlantoaxial dislocation or other conditions requiring fixation of C2. However, the biomechanical stability of this fixation is poorly understood.
OBJECTIVE: To compare and elucidate the biomechanical stability of C2 pedicle screw (C2PS), C2 isthmus screw (C2IS) and C2 short isthmus screw (C2SIS) fixation techniques in atlantoaxial dislocation (AAD).
METHODS: A three-dimensional finite element model (FEM) from occiput to C3 was established and validated from a healthy male volunteer. Three FEMs, C1 pedicle screw (PS)-C2PS, C1PS-C2IS, C1PS-C2SIS were also constructed. The range of motion (ROM) and the maximum von Mises stress under flexion, extension, lateral bending and axial rotation loading were analyzed and compared. The pullout strength of the three fixations for C2 was also evaluated.
RESULTS: C1PS-C2IS model showed the greatest decrease in ROM with flexion, extension, lateral bending and axial rotation. C1PS-C2PS model showed the least ROM reduction under all loading conditions than both C2IS and C2SIS. The C1PS-C2PS model had the largest von Mises stress on the screw under all directions followed by C1PS-C2SIS, and lastly the C1PS-C2IS. Under axial rotation and lateral bending loading, the three models showed the maximum and minimum von Mises stress on the screw respectively. The stress of the three models was mainly located in the connection of the screw and rod. Overall, the maximum screw pullout strength for C2PS, C2IS and C2SIS were 729.41N, 816.62N, 640.54N respectively.
CONCLUSIONS: In patients with atlantoaxial dislocations, the C2IS fixation provided comparable stability, with no significant stress concentration. Furthermore, the C2IS had sufficient pullout strength when compared with C2PS and C2SIS. C2 isthmus screw fixation may be a biomechanically favourable option in cases with AAD. However, future clinical trials are necessary for the evaluation of the clinical outcomes of this technique.