Huang Chenyi, Liu Zongchao, Wei Zhangchao, Fang Zhongxin, Xi Zhipeng, Cai Ping, Li Jingchi
Department of Orthopedics, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, China.
Fluid and Power Machinery Key Laboratory of Ministry of Education, Xihua University, Chengdu, China.
Front Surg. 2023 Jan 12;9:1004642. doi: 10.3389/fsurg.2022.1004642. eCollection 2022.
The fixation-induced biomechanical deterioration will increase the risk of adjacent segment diseases (ASD) after lumbar interbody fusion with Bilateral pedicle screw (BPS) fixation. The accurate adjustment of insertional pedicle screw positions is possible, and published studies have reported its mechanical effects. However, no studies clarified that adjusting insertional screw positions would affect the postoperative biomechanical environment and the risk of ASD. The objective of this study was to identify this issue and provide theoretical references for the optimization of insertional pedicle screw position selections.
The oblique lumbar interbody fusion fixed by BPS with different insertional positions has been simulated in the L4-L5 segment of our previously constructed and validated lumbosacral model. Biomechanical indicators related to ASD have been computed and recorded under flexion, extension, bending, and axial rotation loading conditions.
The change of screw insertional positions has more apparent biomechanical effects on the cranial than the caudal segment. Positive collections can be observed between the reduction of the fixation length and the alleviation of motility compensation and stress concentration on facet cartilages. By contrast, no pronounced tendency of stress distribution on the intervertebral discs can be observed with the change of screw positions.
Reducing the fixation stiffness by adjusting the insertional screw positions could alleviate the biomechanical deterioration and be an effective method to reduce the risk of ASD caused by BPS.
在腰椎椎间融合采用双侧椎弓根螺钉（BPS）固定后，固定引起的生物力学退变会增加相邻节段疾病（ASD）的风险。准确调整置入椎弓根螺钉的位置是可行的，并且已发表的研究报告了其力学效应。然而，尚无研究阐明调整置入螺钉位置会如何影响术后生物力学环境以及ASD的风险。本研究的目的是确定这一问题，并为优化置入椎弓根螺钉位置的选择提供理论参考。
在我们先前构建并验证的腰骶模型的L4-L5节段模拟了不同置入位置的BPS固定的斜外侧腰椎椎间融合。在屈曲、伸展、侧弯和轴向旋转加载条件下计算并记录与ASD相关的生物力学指标。
螺钉置入位置的改变对上位节段的生物力学影响比对下位节段更明显。在固定长度的缩短与小关节软骨上运动代偿和应力集中的减轻之间可观察到正相关。相比之下，随着螺钉位置的改变，椎间盘上应力分布没有明显的趋势。
通过调整置入螺钉位置降低固定刚度可减轻生物力学退变，是降低BPS所致ASD风险的有效方法。
