Relative Nucleus Pulposus Area and Position Alter Disk Joint Mechanics
Relative Nucleus Pulposus Area and Position Alter Disk Joint Mechanics
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相对髓核面积和位置改变椎间盘关节力学
DOI：
10.1115/1.4043029
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
O'Connell, Grace D.
中科院分区：
文献类型：
--
作者：
Yang, Bo;Lu, Yintong;Um, Colin;O'Connell, Grace D.
椎间盘的老化和退变通过组织组成和几何形状的变化来观察，包括髓核（NP）面积的减少。髓核中心位于椎间盘中心的稍后，但髓核大小和位置对椎间盘关节力学的影响还不清楚。我们评估了NP大小和质心位置对双重加载模式下的椎间盘关节力学的影响（即，压缩结合轴向旋转或弯曲）。开发有限元模型（FEM）以改变相对NP面积（NP：盘面积比范围= 0.21-0.60）。我们还通过前后移动NP中心来评估NP位置的影响。我们的研究结果表明，压缩刚度和平均第一主应变与NP尺寸增加。在轴向压缩下，应力从NP分布到瓣环，并且随着轴向旋转，应力朝向NP重新分布。此外，峰值应力更大的磁盘与一个较小的NP面积。在屈曲和伸展过程中，髓核中心位置对椎间盘内压力的影响更大，对于髓核位置更靠后的椎间盘，伸展状态下后环的峰值压力更大。总之，这项研究的结果强调了在计算模型中密切模仿NP大小和位置的重要性，这些模型旨在了解复杂负载期间的应力/应变分布，并制定旨在概括健康椎间盘机械行为的修复策略。
Aging and degeneration of the intervertebral disk are noted by changes in tissue composition and geometry, including a decrease in nucleus pulposus (NP) area. The NP centroid is positioned slightly posterior of the disk's centroid, but the effect of NP size and location on disk joint mechanics is not well understood. We evaluated the effect of NP size and centroid location on disk joint mechanics under dual-loading modalities (i.e., compression in combination with axial rotation or bending). A finite element model (FEM) was developed to vary the relative NP area (NP:Disk area ratio range = 0.21–0.60). We also evaluated the effect of NP position by shifting the NP centroid anteriorly and posteriorly. Our results showed that compressive stiffness and average first principal strains increased with NP size. Under axial compression, stresses are distributed from the NP to the annulus, and stresses were redistributed toward the NP with axial rotation. Moreover, peak stresses were greater for disks with a smaller NP area. NP centroid location had a greater impact on intradiscal pressure during flexion and extension, where peak pressures in the posterior annulus under extension was greater for disks with a more posteriorly situated NP. In conclusion, the findings from this study highlight the importance of closely mimicking NP size and location in computational models that aim to understand stress/strain distribution during complex loading and for developing repair strategies that aim to recapitulate the mechanical behavior of healthy disks.