Orthopaedic Biomechanics, Department of Biomedical Engineering, Eindhoven University of Technology, Den Dolech 2, 5612AZ Eindhoven, the Netherlands; Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, P. Debyelaan 25, 6229HX Maastricht, the Netherlands.
Department of Orthopaedic Surgery, Research School CAPHRI, Maastricht University Medical Center, P. Debyelaan 25, 6229HX Maastricht, the Netherlands.
Clin Biomech (Bristol). 2023 Aug;108:106071. doi: 10.1016/j.clinbiomech.2023.106071. Epub 2023 Aug 12.
Proximal junctional failure is a common complication attributed to the rigidity of long pedicle screw fixation constructs used for surgical correction of adult spinal deformity. Semi-rigid junctional fixation achieves a gradual transition in range of motion at the ends of spinal instrumentation, which could lead to reduced junctional stresses, and ultimately reduce the incidence of proximal junctional failure. This study investigates the biomechanical effect of different semi-rigid junctional fixation techniques in a T8-L3 finite element spine segment model.
First, degeneration of the intervertebral disc was successfully implemented by altering the height. Second, transverse process hooks, one- and two-level clamped tapes, and one- and two-level knotted tapes instrumented proximally to three-level pedicle screw fixation were validated against ex vivo range of motion data of a previous study. Finally, the posterior ligament complex forces and nucleus pulposus stresses were quantified.
Simulated range of motions demonstrated the fidelity of the general model and modelling of semi-rigid junctional fixation techniques. All semi-rigid junctional fixation techniques reduced the posterior ligament complex forces at the junctional zone compared to pedicle screw fixation. Transverse process hooks and knotted tapes reduced nucleus pulposus stresses, whereas clamped tapes increased nucleus pulposus stresses at the junctional zone.
The relationship between the range of motion transition and the reductions in posterior ligament complex and nucleus pulposus stresses was complex and dependent on the fixation techniques. Clinical trials are required to compare the effectiveness of semi-rigid junctional fixation techniques in terms of reducing proximal junctional failure incidence rates.
近端交界性失败是一种常见的并发症，归因于用于矫正成人脊柱畸形的长椎弓根螺钉固定结构的刚性。半刚性交界性固定在脊柱器械的末端实现了运动范围的逐渐过渡，这可能导致交界性应力降低，并最终降低近端交界性失败的发生率。本研究调查了 T8-L3 有限元脊柱节段模型中不同半刚性交界性固定技术的生物力学效应。
首先，通过改变高度成功地实现了椎间盘的退变。其次，横向过程钩、单级和两级夹片以及单级和两级打结片与之前研究的三维椎弓根螺钉固定的近侧进行了验证，以确定其运动范围。最后，定量了后纵韧带复合体的力和髓核的应力。
模拟运动范围展示了一般模型和半刚性交界性固定技术建模的准确性。与椎弓根螺钉固定相比，所有半刚性交界性固定技术均降低了交界区的后纵韧带复合体的力。横向过程钩和打结片降低了髓核的应力，而夹片则增加了交界区的髓核的应力。
运动范围过渡与后纵韧带复合体和髓核的应力降低之间的关系是复杂的，取决于固定技术。需要进行临床试验，以比较半刚性交界性固定技术在降低近端交界性失败发生率方面的有效性。
