METHODS: A complete lumbar spine model, M1, was built using 3D finite elements, and models M2 and M3 were constructed to simulate the intraoperative removal of the superior articular process of L5 using a trephine saw with diameters of 5 mm and 8.5 mm, respectively, and applying normal physiological loads on the different models to simulate six working conditions-anterior flexion, posterior extension, left-right lateral bending, and left-right rotation-to investigate the displacement and facet joint stress change of the surgical segment, and the disc stress change of the surgical and adjacent segments.
RESULTS: Compared with the M1 model, the M2 and M3 models showed decreased stress at the L4-5 left FJ and a significant increase in stress at the right FJ in forward flexion. In the M2 and M3 models, the L4-5 FJ stresses were significantly greater in left lateral bending or left rotation than in right lateral bending or right rotation. The right FJ stress in M3 was greater during left rotation than that in M2, and that in M2 was greater than that in M1. The L4-5disc stress in the M3 model was greater during posterior extension than that in the M1 and M2 models. The L4-5disc stress in the M3 model was greater in the right rotation than in the M2 model, and that in the M2 model was greater than that in the M1 model.
CONCLUSIONS: Foraminoplasty using large-channel endoscopy could increase the stress on the FJ and disc of the surgical segment, which suggested unnecessary and excessive resection should be avoided in PTED to minimize biomechanical disruption.
方法:完整的腰椎模型,M1是使用3D有限元建造的,并建立模型M2和M3,以模拟使用直径为5mm和8.5mm的环钻锯去除L5的上关节突,分别,并在不同的模型上施加正常的生理负荷来模拟六种工作条件——前屈,后延伸,左右横向弯曲,和左右旋转-研究手术节段的位移和小关节应力变化,以及手术和邻近节段的椎间盘应力变化。
结果:与M1模型相比,M2和M3模型显示,前屈时L4-5左侧FJ应力降低,右侧FJ应力显著增加.在M2和M3型号中,L4-5FJ应力在左侧弯曲或向左旋转中明显大于在右侧弯曲或向右旋转中。M3的右FJ应力在左旋转过程中大于M2,M2大于M1。M3模型的L4-5椎间盘应力在向后延伸期间大于M1和M2模型。M3模型中的L4-5disc应力在右旋转中大于M2模型中的应力,M2模型中的数值大于M1模型中的数值。
结论:使用大通道内窥镜检查的椎间孔成形术可增加对FJ和手术段椎间盘的应力,这表明在PTED中应避免不必要和过度的切除,以最大程度地减少生物力学破坏。