Is Cervical Sagittal Imbalance a Risk Factor for Adjacent Segment Pathomechanics After Multilevel Fusion?
Is Cervical Sagittal Imbalance a Risk Factor for Adjacent Segment Pathomechanics After Multilevel Fusion?
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DOI：
10.1097/brs.0000000000001316
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发表时间：
2016-05-01
期刊：
影响因子：
3
通讯作者：
Ghanayem, Alexander J.
中科院分区：
文献类型：
--
作者：
Patwardhan, Avinash G.;Khayatzadeh, Saeed;Ghanayem, Alexander J.
研究设计。使用人体脊柱标本进行生物力学研究。目的。本研究的目的是评估颈椎矢状不平衡的存在是否是增加颈椎多级融合附近椎间盘机械负担的独立危险因素。背景数据摘要。 C2铅垂线和C7椎体之间的水平偏移距离（C2-C7矢状垂直轴（SVA））或连接C2和C7椎体的线与垂直线形成的角度（C2-C7倾斜角）用作评估颈椎矢状平衡的放射学测量。有III级临床证据表明，后凸融合或整体脊柱矢状面错位引起的矢状面失衡可能会增加邻近节段病理的风险。方法。首先对 13 个人类尸体颈椎（枕骨-T1；年龄：50.6 岁；范围：21-67）在原始完整状态下进行测试，然后在 C4-C6 上安装仪器以模拟原位两级融合。使用先前验证的实验模型对样本进行测试，该模型可以测量脊柱对规定不平衡的反应。在不同大小的 C2-C7 倾斜角（或 C2-C7 SVA）下评估融合对 C3-C4 和 C6-C7 椎间盘（融合上方和下方）的节段角度对准和椎间盘内压力的影响。结果。与融合前状态相比，跨 C4-C6 节段的原位融合需要增加屈曲角度，并导致融合下方的 C6-C7 椎间盘内压力增加，以适应 C2-C7 倾斜角或 C2-C7 SVA 的相同增加 (P < 0.05)。随着C2-C7倾斜角或SVA的增加，由于融合而导致的相邻节段机械负担变得更大。结论。由区域和/或整体脊柱矢状错位引起的颈椎矢状失衡可能会加剧多节段融合后相邻节段的病理力学，应在手术计划期间予以考虑。
Study Design. A biomechanical study using human spine specimens.Objective. The aim of this study was to assess whether the presence of cervical sagittal imbalance is an independent risk factor for increasing the mechanical burden on discs adjacent to cervical multilevel fusions.Summary of Background Data. The horizontal offset distance between the C2 plumbline and C7 vertebral body (C2-C7 Sagittal Vertical Axis (SVA)) or the angle made with vertical by a line connecting the C2 and C7 vertebral bodies (C2-C7 tilt angle) are used as radiographic measures to assess cervical sagittal balance. There is level III clinical evidence that sagittal imbalance caused by kyphotic fusions or global spinal sagittal malalignment may increase the risk of adjacent segment pathology.Methods. Thirteen human cadaveric cervical spines (Occiput-T1; age: 50.6 years; range: 21-67) were tested first in the native intact state and then after instrumentation across C4-C6 to simulate in situ two-level fusion. Specimens were tested using a previously validated experimental model that allowed measurement of spinal response to prescribed imbalance. The effects of fusion on segmental angular alignments and intradiscal pressures in the C3-C4 and C6-C7 discs, above and below the fusion, were evaluated at different magnitudes of C2-C7 tilt angle (or C2-C7 SVA).Results. When compared with the pre-fusion state, in situ fusion across C4-C6 segments required increased flexion angulation and resulted in increased intradiscal pressure at the C6-C7 disc below the fusion in order to accommodate the same increase in C2-C7 tilt angle or C2-C7 SVA (P < 0.05). The adjacent segment mechanical burden due to fusion became greater with increasing C2-C7 tilt angle or SVA.Conclusion. Cervical sagittal imbalance arising from regional and/or global spinal sagittal malalignment may play a role in exacerbating adjacent segment pathomechanics after multilevel fusion and should be considered during surgical planning.