Chen Yun-Lin, Lai Ou-Jie, Wang Yang, Ma Wei-Hu, Chen Qi-Xin
Department of Spine Surgery, Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Department of Spine Surgery, Ningbo No. 6 Hospital, Ningbo, China.
Comput Methods Biomech Biomed Engin. 2020 Jul;23(9):548-555. doi: 10.1080/10255842.2020.1745784. Epub 2020 Mar 30.
To analyze the biomechanical stability of a redesigned cage, a new lateral plate and the effect of length of cage in CLIF, an L4-L5 finite element model was performed. Six different internal fixation methods were designed and operated under six conditions (Stand-alone CLIF; CLIF with unilateral pedicle screws (CLIF + UPS); CLIF with bilateral pedicle screws (CLIF + BPS); CLIF with lateral plate (CLIF + LP); CLIF with lateral plate and unilateral pedicle screws (CLIF + LP + UPS); CLIF with lateral plate and bilateral pedicle screws (CLIF + LP + BPS)). Ranges of motion (ROM) and stress distribution were evaluated. The effect of the length of cage was analyzed. The ROMs of stand-alone CLIF group and other internal fixation groups were decreased by >90% compared with the intact group. The CLIF + LP + BPS group has the minimum ROM. The CLIF + LP group has smaller ROM than stand-alone group. The stand-alone group has the minimum stress except for extension condition. The CLIF + LP model has less ROM, but a greater stress load was observed in the lateral plate. As for the length of cage, the largest stress is located at the junction between cage and distal end plate, especially in the epiphyseal ring and cortical compact. We conduct a new 'cylinder wall theory' that the cage should be placed to cover the epiphyseal ring. We recommend the length of cage should cover the epiphyseal ring to reduce the subsidence of cage.
为分析重新设计的椎间融合器、新型侧板以及椎间融合器长度在腰椎椎间融合术（CLIF）中的生物力学稳定性，构建了L4 - L5有限元模型。设计了六种不同的内固定方法，并在六种工况下进行操作（单纯CLIF；CLIF联合单侧椎弓根螺钉（CLIF + UPS）；CLIF联合双侧椎弓根螺钉（CLIF + BPS）；CLIF联合侧板（CLIF + LP）；CLIF联合侧板和单侧椎弓根螺钉（CLIF + LP + UPS）；CLIF联合侧板和双侧椎弓根螺钉（CLIF + LP + BPS））。评估了活动范围（ROM）和应力分布。分析了椎间融合器长度的影响。与完整组相比，单纯CLIF组及其他内固定组的ROM均降低了90%以上。CLIF + LP + BPS组的ROM最小。CLIF + LP组的ROM比单纯组小。除伸展工况外，单纯组的应力最小。CLIF + LP模型的ROM较小，但侧板处观察到更大的应力负荷。至于椎间融合器的长度，最大应力位于椎间融合器与远端终板的交界处，尤其是在骨骺环和皮质骨密质处。我们提出了一种新的“圆柱壁理论”，即椎间融合器应放置以覆盖骨骺环。我们建议椎间融合器的长度应覆盖骨骺环以减少椎间融合器的下沉。
