Fan Wei, Zhang Chi, Zhang Dong-Xiang, Guo Li-Xin, Zhang Ming, Wang Qing-Dong
School of Mechanical Engineering and Automation, Northeastern University, Shenyang 110819, China.
Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
J Biomech Eng. 2023 Jun 1;145(6). doi: 10.1115/1.4056768.
Rigid interspinous process fixation (RIPF) has been recently discussed as an alternative to pedicle screw fixation (PSF) for reducing trauma in lumbar interbody fusion (LIF) surgery. This study aimed to investigate biomechanics of the lumbar spine with RIPF, and also to compare biomechanical differences between two postoperative stages (before and after bony fusion). Based on an intact finite-element model of lumbosacral spine, the models of single-level LIF with RIPF or conventional PSF were developed and were computed for biomechanical responses to the moments of four physiological motions using hybrid testing protocol. It was found that compared with PSF, range of motion (ROM), intradiscal pressure (IDP), and facet joint forces (FJF) at adjacent segments of the surgical level for RIPF were decreased by up to 8.4%, 2.3%, and 16.8%, respectively, but ROM and endplate stress at the surgical segment were increased by up to 285.3% and 174.3%, respectively. The results of comparison between lumbar spine with RIPF before and after bony fusion showed that ROM and endplate stress at the surgical segment were decreased by up to 62.6% and 40.4%, respectively, when achieved to bony fusion. These findings suggest that lumbar spine with RIPF as compared to PSF has potential to decrease the risk of adjacent segment degeneration but might have lower stability of surgical segment and an increased risk of cage subsidence; When achieved bony fusion, it might be helpful for the lumbar spine with RIPF in increasing stability of surgical segment and reducing failure of bone contact with cage.
最近，刚性棘突间固定（RIPF）作为椎弓根螺钉固定（PSF）的替代方法被讨论，用于减少腰椎椎间融合（LIF）手术中的创伤。本研究旨在研究采用RIPF的腰椎生物力学，并比较两个术后阶段（骨融合前后）的生物力学差异。基于腰骶椎完整的有限元模型，建立了采用RIPF或传统PSF的单节段LIF模型，并使用混合测试方案计算其对四种生理运动力矩的生物力学响应。结果发现，与PSF相比，RIPF手术节段相邻节段的活动范围（ROM）、椎间盘内压力（IDP）和小关节力（FJF）分别降低了8.4%、2.3%和16.8%，但手术节段的ROM和终板应力分别增加了285.3%和174.3%。对采用RIPF的腰椎骨融合前后的比较结果表明，实现骨融合时，手术节段的ROM和终板应力分别降低了62.6%和40.4%。这些发现表明，与PSF相比，采用RIPF的腰椎有可能降低相邻节段退变的风险，但手术节段的稳定性可能较低，椎间融合器下沉的风险增加；实现骨融合时，可能有助于采用RIPF的腰椎提高手术节段的稳定性并减少骨与椎间融合器接触失败的情况。
