Dept of Spinal Surgery, The First Affiliated Hospital of Guangzhou Medical University, 151 Yanjiang West Road, Guangzhou, Guangdong, China 510120.
MOE Key Laboratory of Disaster Forecast and Control in Engineering, Institute of Applied Mechanics, Jinan University, Guangzhou, Guangdong, China 510632.
Biomed Res Int. 2021 May 15;2021:5542595. doi: 10.1155/2021/5542595. eCollection 2021.
The combination of screw fixation and cage can provide stability in lumbar interbody fusion (LIF), which is an important technique to treat lumbar degeneration diseases. As the narrow surface cage is developed in oblique lateral lumbar interbody fusion (OL-LIF), screw fixation should be improved at the same time. We used the finite element (FE) method to investigate the biomechanics response by three different ways of screw fixation in OL-LIF.
Using a validated FE model, OL-LIF with 3 different screw fixations was simulated, including percutaneous transverterbral screw (PTVS) fixation, percutaneous cortical bone trajectory screw (PCBTS) fixation, and percutaneous transpedical screw (PPS) fixation. Range of motion (ROM), vertebral body displacement, cage displacement, cage stress, cortical bone stress, and screw stress were compared.
ROM in FE models significantly decreased by 84-89% in flexion, 91-93% in extension, 78-89% in right and left lateral bending, and 73-82% in right and left axial rotation compared to the original model. The maximum displacement of the vertebral body and the cage in six motions except for the extension of model PTVS was the smallest among models. Meanwhile, the model PTVS had the higher stress of screw-rods system and also the lowest stress of cage. In all moments, the maximum stresses of the cages were lower than their yield stress.
Three screw fixations can highly restrict the surgical functional spinal unit (FSU). PTVS provided the better stability than the other two screw fixations. It may be a good choice for OL-LIF.
螺钉固定与 cage 的结合为腰椎体间融合术（LIF）提供了稳定性，这是治疗腰椎退行性疾病的重要技术。随着斜外侧腰椎体间融合术（OL-LIF）中出现窄面 cage，同时需要改进螺钉固定。我们使用有限元（FE）方法研究了三种不同螺钉固定方式在 OL-LIF 中的生物力学反应。
使用经过验证的 FE 模型，模拟了三种不同螺钉固定的 OL-LIF，包括经皮椎体螺钉（PTVS）固定、经皮皮质骨轨道螺钉（PCBTS）固定和经皮椎弓根螺钉（PPS）固定。比较了活动度（ROM）、椎体位移、cage 位移、cage 应力、皮质骨应力和螺钉应力。
FE 模型中的 ROM 在屈伸时显著降低了 84-89%，在伸展时降低了 91-93%，在左右侧屈时降低了 78-89%，在左右轴向旋转时降低了 73-82%，与原始模型相比。在除了 PTVS 模型伸展以外的六个运动中，椎体和 cage 的最大位移在模型中最小。同时，PTVS 模型的螺钉-杆系统的应力较高，cage 的应力较低。在所有时刻，cage 的最大应力均低于其屈服应力。
三种螺钉固定均可高度限制手术功能脊柱单元（FSU）。PTVS 提供的稳定性优于其他两种螺钉固定方式。它可能是 OL-LIF 的一个较好选择。
