Mok James M, Lin Ye, Tafur Julio Castillo, Diaz Roberto Leonardo, Amirouche Farid
NorthShore University HealthSystem, Skokie, IL, USA.
Department of Orthopaedics, University of Illinois at Chicago, Chicago, IL, USA.
Neurospine. 2023 Jun;20(2):478-486. doi: 10.14245/ns.2244734.367. Epub 2023 Jun 30.
Lumbar lateral interbody fusion (LLIF) allows placement of large interbody cages while preserving ligamentous structures important for stability. Multiple clinical and biomechanical studies have demonstrated the feasibility of stand-alone LLIF in single-level fusion. We sought to compare the stability of 4-level stand-alone LLIF utilizing wide (26 mm) cages with bilateral pedicle screw and rod fixation.
Eight human cadaveric specimens of L1-5 were included. Specimens were attached to a universal testing machine (MTS 30/G). Flexion, extension, and lateral bending were attained by applying a 200 N load at a rate of 2 mm/sec. Axial rotation of ± 8° of the specimen was performed at 2°/sec. Three-dimensional specimen motion was recorded using an optical motion-tracking device. Specimens were tested in 4 conditions: (1) intact, (2) bilateral pedicle screws and rods, (3) 26-mm stand-alone LLIF, (4) 26-mm LLIF with bilateral pedicle screws and rods.
Compared to the stand-alone LLIF, bilateral pedicle screws and rods had 47% less range of motion in flexion-extension (p < 0.001), 21% less in lateral bending (p < 0.05), and 20% less in axial rotation (p = 0.1). The addition of bilateral posterior instrumentation to the stand-alone LLIF resulted in decreases of all 3 planes of motion: 61% in flexion-extension ( p < 0.001), 57% in lateral bending (p < 0.001), 22% in axial rotation (p = 0.002).
Despite the biomechanical advantages associated with the lateral approach and 26 mm wide cages, stand-alone LLIF for 4-level fusion is not equivalent to pedicle screws and rods.
腰椎外侧椎间融合术（LLIF）可在保留对稳定性至关重要的韧带结构的同时置入大型椎间融合器。多项临床和生物力学研究已证明单节段融合中单纯LLIF的可行性。我们试图比较使用宽（26毫米）融合器并结合双侧椎弓根螺钉和棒固定的4节段单纯LLIF的稳定性。
纳入8例L1 - 5节段的人体尸体标本。标本连接到万能试验机（MTS 30/G）上。通过以2毫米/秒的速度施加200牛的载荷来实现前屈、后伸和侧方弯曲。标本以2°/秒的速度进行±8°的轴向旋转。使用光学运动跟踪装置记录标本的三维运动。标本在4种情况下进行测试：（1）完整状态；（2）双侧椎弓根螺钉和棒；（3）使用26毫米的单纯LLIF；（4）使用26毫米的LLIF并结合双侧椎弓根螺钉和棒。
与单纯LLIF相比，双侧椎弓根螺钉和棒在前屈 - 后伸时的活动度减少47%（p < 0.001），侧方弯曲时减少21%（p < 0.05），轴向旋转时减少20%（p = 0.1）。在单纯LLIF基础上增加双侧后路内固定导致所有三个运动平面的活动度均降低：前屈 - 后伸时降低61%（p < 0.001），侧方弯曲时降低57%（p < 0.001），轴向旋转时降低22%（p = 0.002）。
尽管外侧入路和26毫米宽的融合器具有生物力学优势，但用于4节段融合的单纯LLIF并不等同于椎弓根螺钉和棒。
