The development of adjacent segment degeneration (ASD) following ACDF is well established. There is no analytical study related to effects of plate profile on the biomechanics of the adjacent-level after ACDF. This study aimed to test the effects of plate profile on the adjacent-level biomechanics after single-level anterior cervical discectomy and fusion (ACDF). A three-dimensional finite element model (FEM) of an intact C2–T1 segment was built and validated. From this intact model, two instrumentation models were constructed with the anchored zero-profile spacer or the standard plate-interbody spacer after a C5-C6 corpectomy and fusion. Motion patterns, the stresses in the disc, the endplate, and the facet joint at the levels cephalad and caudal to the fusion were assessed. Compared with the normal condition, the biomechanical responses in the adjacent levels were increased after fusion. Relative to the intact model, the average increase of range of motion (ROM) and stresses in the endplate, the disc, and the facet of the zero-profile spacer fusion model were slightly lower than that of the standard plate-interbody spacer fusion model. The kinematics ROM and stress variations above fusion segment were larger than that below. The biomechanical features of the adjacent segment after fusion were most affected during extension. The FE analysis indicated that plate profile may have an impact on the biomechanics of the adjacent-level after a single-level ACDF. The impact may be long-term and cumulative. The current findings may help explain the decreasing incidence of ASD complications in the patients using zero-profile spacer compared with the patients using cage and plate construct.

中文翻译：

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单级前颈椎椎间融合器与固定零位间隔器与笼板结构融合后的相邻级生物力学：有限元研究。

在ACDF之后，邻近节段退变（ASD）的发展已得到充分确立。没有关于ACDF后板轮廓对相邻层生物力学影响的分析研究。这项研究旨在测试单层前路颈椎间盘摘除术和融合术（ACDF）后板轮廓对邻近水平生物力学的影响。建立并验证了完整的C2-T1段的三维有限元模型（FEM）。从这个完整的模型中，在C5-C6切除并融合后，使用锚定的零轮廓间隔器或标准板间间隔器构建了两个仪器模型。评估了运动模式，椎间盘，终板和小关节在融合的头端和尾端的应力。与正常情况相比 融合后，相邻水平的生物力学响应增加。相对于完整模型，零剖面垫片融合模型的端板，圆盘和刻面的运动范围（ROM）和应力的平均增加量略低于标准板间垫片融合模型的运动范围和应力。融合段以上的运动学ROM和应力变化大于下方。融合后相邻节段的生物力学特征在延伸过程中受影响最大。有限元分析表明，在单级ACDF处理后，板的轮廓可能会对相邻级的生物力学产生影响。影响可能是长期的和累积的。