McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, University of Pennsylvania, Philadelphia, PA, USA.
Drexel University School of Biomedical Engineering, Science and Health Systems, Philadelphia, PA, USA.
J Anat. 2021 Apr;238(4):986-998. doi: 10.1111/joa.13349. Epub 2020 Nov 17.
Intervertebral disc (IVD) degeneration and associated back pain place a significant burden on the population. IVD degeneration is a progressive cascade of cellular, compositional, and structural changes, which results in a loss of disc height, disorganization of extracellular matrix architecture, tears in the annulus fibrosus which may involve herniation of the nucleus pulposus, and remodeling of the bony and cartilaginous endplates (CEP). These changes to the IVD often occur concomitantly, across the entire motion segment from the disc subcomponents to the CEP and vertebral bone, making it difficult to determine the causal initiating factor of degeneration. Furthermore, assessments of the subcomponents of the IVD have been largely qualitative, with most studies focusing on a single attribute, rather than multiple adjacent IVD substructures. The objective of this study was to perform a multiscale and multimodal analysis of human lumbar motion segments across various length scales and degrees of degeneration. We performed multiple assays on every sample and identified several correlations between structural and functional measurements of disc subcomponents. Our results demonstrate that with increasing Pfirrmann grade there is a reduction in disc height and nucleus pulposus T2 relaxation time, in addition to alterations in motion segment macromechanical function, disc matrix composition and cellular morphology. At the cartilage endplate-vertebral bone interface, substantial remodeling was observed coinciding with alterations in micromechanical properties. Finally, we report significant relationships between vertebral bone and nucleus pulposus metrics, as well as between micromechanical properties of the endplate and whole motion segment biomechanical parameters, indicating the importance of studying IVD degeneration as a whole organ.
椎间盘（IVD）退变及其相关的背痛给人群带来了巨大的负担。IVD 退变是细胞、组成和结构变化的渐进级联反应，导致椎间盘高度丧失、细胞外基质结构紊乱、纤维环撕裂，可能涉及髓核突出，以及骨和软骨终板（CEP）的重塑。这些 IVD 的变化通常同时发生，跨越整个运动节段，从椎间盘的亚组分到 CEP 和椎骨，使得很难确定退变的起始因素。此外，对 IVD 亚组分的评估在很大程度上是定性的，大多数研究集中在单个属性上，而不是多个相邻的 IVD 亚结构上。本研究的目的是对不同退变程度的人类腰椎运动节段进行多尺度和多模态分析。我们对每个样本进行了多次检测，并确定了椎间盘亚组分的结构和功能测量之间的几个相关性。我们的研究结果表明，随着 Pfirrmann 分级的增加，椎间盘高度和髓核 T2 弛豫时间降低，此外，运动节段宏观力学功能、椎间盘基质组成和细胞形态也发生改变。在软骨终板-椎骨界面，观察到与微观力学特性改变相关的大量重塑。最后，我们报告了椎体和髓核指标之间以及终板的微观力学特性和整个运动节段生物力学参数之间的显著关系，表明研究整个 IVD 退变的重要性。
