Wang Tianhao, Cai Zhihua, Zhao Yongfei, Wang Wei, Zheng Guoquan, Wang Zheng, Wang Yan
Department of Orthopaedics, Southwest Hospital, Third Military Medical University, Chongqing, China; Department of Orthopaedics, General Hospital of Chinese People's Liberation Army, Beijing, China.
School of Electromechanical Engineering, Hunan University of Science and Technology, Xiangtan, China.
World Neurosurg. 2019 Mar;123:e294-e302. doi: 10.1016/j.wneu.2018.11.154. Epub 2018 Nov 26.
To develop finite element models of spine following osteotomy and evaluate the effect of number and location of cross-links (CLs) on long-segment instrumentation.
A finite element model of instrumented spine following osteotomy was created from computed tomography images of a postoperative male patient with thoracolumbar kyphotic deformity. Five fixation models were established to simulate different number and location of CLs. Four loading conditions (flexion, extension, lateral bending, and axial rotation) were applied on the models. Range of motion (ROM), maximum value and distribution of stress on implants, and stress on vertebrae were compared between models.
With increased number of CLs, average ROM of instrumented segments was reduced by 2.37%, 1.89%, and 2.49% in flexion, extension, and lateral bending. ROM was reduced by 21.98% in loading axial rotation condition. With increased number of CLs, ROM tended to be limited. Peak stresses were located on rods during axial rotation, on proximal pedicle screws during flexion, and on the osteotomy site during extension and lateral bending. CLs had an effect of dispersing stress concentration.
The application of CLs enhanced the rigidity of the construct. With increased number of CLs, ROM of the construct was decreased, especially in axial rotation. CLs can also disperse the stress concentration. After comparing various CL configurations in different motion conditions, we believe that the optimal method is to place 2 CLs at the osteotomy site and the proximal segment.
建立截骨术后脊柱的有限元模型，并评估横向连接（CL）的数量和位置对长节段内固定的影响。
根据一名胸腰椎后凸畸形男性患者术后的计算机断层扫描图像，创建截骨术后脊柱内固定的有限元模型。建立了五个固定模型，以模拟不同数量和位置的CL。对模型施加四种加载条件（前屈、后伸、侧弯和轴向旋转）。比较各模型之间的活动度（ROM）、植入物上应力的最大值和分布以及椎体上的应力。
随着CL数量的增加，在前屈、后伸和侧弯时，内固定节段的平均ROM分别降低了2.37%、1.89%和2.49%。在轴向旋转加载条件下，ROM降低了21.98%。随着CL数量的增加，ROM趋于受限。轴向旋转时峰值应力位于棒上，前屈时位于近端椎弓根螺钉上，后伸和侧弯时位于截骨部位。CL具有分散应力集中的作用。
CL的应用增强了内固定结构的刚度。随着CL数量的增加，内固定结构的ROM降低，尤其是在轴向旋转时。CL还可以分散应力集中。在比较不同运动条件下的各种CL配置后，我们认为最佳方法是在截骨部位和近端节段放置2个CL。
