基于ABAQUS的三段式螺钉的力学性能研究

ABAQUS-Based Study of the Mechanical Properties of Three-Stage Screws

摘要: 目的：针对骨质疏松症患者在腰椎融合内固定术后出现邻近关节退变、损伤神经血管等并发症的情况，为此本文设计了一款三段式螺钉并通过仿真软件对手术模型进行分析。方法：基于人体腰椎CT数据建立L3~L5腰椎有限元模型，在腰椎模型上分别建立同尺寸的传统椎弓螺钉内固定M1模型和新型螺钉内固定M2模型，模拟人体在屈伸、侧弯和旋转六种生理活动运动状态。分析在不同骨质下三段式螺钉的最大von Mises应力及应力分布情况、不同工况下腰椎模型活动度。结果：在两种骨质情况下，M2模型在前屈、左右侧弯、左右轴向旋转工况下活动度更大，与健康未植入模型更接近；此外，在骨质疏松情况下，M2模型螺钉在前伸、后屈、左右旋转工况下应力峰值较M1模型降低16.56%、4.67%、23.08%、22.44%。结论：在两种骨量下，采用三段式螺钉可以有限避免术后关节活动度过分受限引起的术后并发症；在骨质疏松条件下，使用三段式螺钉固定可以降低椎弓根螺钉的应力峰值，发生断裂的风险更低。

Abstract: Objective: In order to deal with the complications such as degeneration of adjacent joints and damage to neurovascular and so on after lumbar fusion internal fixation in patients with osteoporosis, for this reason, this paper designs a three-stage screw and analyzes the surgical model by simulation software. Methods: A finite element model of L3~L5 lumbar spine was established based on the CT data of human lumbar spine, and M1 model of traditional pedicle screw internal fixation and M2 model of new screw internal fixation of the same size were established on the lumbar spine model to simulate the six physiological activities of the human body in the flexion-extension, lateral bending and rotation movement state. The maximum von Mises stresses and stress distributions of the three-stage screws were analyzed under different bone qualities, as well as the mobility of the lumbar spine model under different working conditions. Results: Under two bone qualities, the M2 model had greater mobility under forward flexion, left and right lateral bending, and left and right axial rotation working conditions, which was closer to the healthy unimplanted model; moreover, under osteoporotic conditions, the peak stresses of the screws in the M2 model under anterior extension, posterior flexion, and left and right rotation working conditions were reduced by 16.56%, 4.67%, 23.08%, and 22.44% compared with that in the M1 model. Conclusion: The use of three-stage screws can limitedly avoid postoperative complications caused by excessive restriction of joint mobility after surgery in both bone volumes; in osteoporotic conditions, the use of three-stage screw fixation can reduce the peak stress value of pedicle screws, and the risk of fracture is lower.