Pei Baoqing, Lu Da, Wu Xueqing, Xu Yangyang, Ma Chenghao, Wu Shuqin
Beijing Key Laboratory for Design and Evaluation Technology of Advanced Implantable & Interventional Medical Devices, Beijing Advanced Innovation Center for Biomedical Engineering, School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China.
School of Big Data and Information, Shanxi College of Technology, Shuozhou 036000, China.
Int J Environ Res Public Health. 2022 Feb 12;19(4):2057. doi: 10.3390/ijerph19042057.
Early onset scoliosis (EOS) is emerging as a serious threat to children's health and is the third largest threat to their health after myopia and obesity. At present, the growing rod technique (GRT), which allows patients to regain a well-balanced sagittal profile, is commonly considered as an invasive surgical procedure for the treatment of EOS. However, the risk of postoperative complications and instrumentation breakage remains high, which is mainly related to the choice of fixed mode. Several authors have studied primary stability and instrumentation loads, neglecting the mechanical transmission of the spinal long-segment model in different growth phases, which is fundamental to building a complete biomechanical environment. The present study aimed to investigate the kinematic and biomechanical properties that occur after GRT, across the long spinal structure and the posterior instrumentation, which are affected by unilateral or bilateral fixation. Accordingly, spinal segments (C6-S1) were loaded under flexion (Flex), extension (Ext), left lateral bending (LB), right lateral bending (RB), left torsion (LT), and right torsion (RT) using 11 established spinal models, which were from three growth phases. The stress distribution, spinal and intervertebral range of motion (ROM), counter torque of the vertebra, and bracing force on the rods were measured. The results showed that bilateral posterior fixation (BPF) is more stable than unilateral posterior fixation (UPF), at the expense of more compensations for the superior adjacent segment (SAS), especially when the superior fixed segment is closer to the head. Additionally, the bracing force of the instrumentation on the spine increases as the Cobb angle decreases. Accordingly, this biomechanical analysis provides theoretical suggestions for the selection of BPF or UPF and fixed segments in different growing phases.
早发性脊柱侧弯（EOS）正成为对儿童健康的严重威胁，是仅次于近视和肥胖的第三大健康威胁。目前，能让患者重新获得良好矢状面平衡的生长棒技术（GRT）通常被视为治疗EOS的一种侵入性外科手术。然而，术后并发症和内固定断裂的风险仍然很高，这主要与固定方式的选择有关。几位作者研究了初始稳定性和内固定负荷，却忽略了不同生长阶段脊柱长节段模型的力学传递，而这对于构建完整的生物力学环境至关重要。本研究旨在探究GRT术后，在整个脊柱长结构和后路内固定中，受单侧或双侧固定影响而出现的运动学和生物力学特性。因此，使用来自三个生长阶段的11个已建立的脊柱模型，对脊柱节段（C6-S1）进行前屈（Flex）、后伸（Ext）、左侧弯（LB）、右侧弯（RB）、左旋（LT）和右旋（RT）加载。测量了应力分布、脊柱和椎间活动度（ROM）、椎体的反扭矩以及棒上的支撑力。结果表明，双侧后路固定（BPF）比单侧后路固定（UPF）更稳定，但代价是对上位相邻节段（SAS）有更多代偿，尤其是当上位固定节段更靠近头部时。此外，随着Cobb角减小，内固定对脊柱的支撑力增加。因此，这种生物力学分析为不同生长阶段BPF或UPF以及固定节段的选择提供了理论建议。
