Reduced Shear Modulus and Altered Lamellar Morphology of the Outer Annulus Fibrosus in Painful Intervertebral Disc Degeneration Compared With Tissue From Non-Surgical Controls

IF 3.9 3区医学 Q1 ORTHOPEDICS

JOR Spine Pub Date : 2025-10-08 DOI:10.1002/jsp2.70123

Taylor J. Bader, Manmeet Dhiman, Lucas Lo Vercio, Jacques Bouchard, Fred Nicholls, Nathan Evaniew, Bradley Jacobs, Kenneth C. Thomas, Paul Salo, David A. Hart, Neil A. Duncan, Ganesh Swamy

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Abstract

Background

Stability of the spine and intervertebral disc (IVD) integrity is enabled by the highly organized fibrocartilaginous annulus fibrosus (AF). The shear properties of the AF are important in maintaining IVD integrity. AF shear mechanics in degenerative disc (DD) remain underexplored, especially in comparing minimally degenerative (non-DD) and symptomatic DD individuals. This study measured tissue mechanical properties (AF simple shear modulus and dynamic shear properties) and examined structure (with optical coherence tomography (OCT)) in surgical DD and non-DD control individuals.

Methods

Whole AF tissue samples were collected from non-DD donors (N = 13) and DD surgical individuals (N = 30). Two anterior outer AF (OAF) 5 mm cubes were sectioned from each sample and subjected to shear in two orientations, radial (coronal plane, G1) and circumferential (sagittal plane, G2). Tissues underwent static shear and dynamic shear protocols to a maximum of 10% shear strain. Following mechanical tests, average lamellar thickness was assessed using OCT.

Results

Static shear moduli were significantly reduced for DD tissue compared to non-DD in both the radial (G1) (non-DD: 83.0 ± 41.3 kPa, DD: 24.1 ± 23.7 kPa) and the circumferential (G2) (non-DD: 226.2 ± 81.9 kPa, DD: 54.0 ± 40.2 kPa) orientations (p < 0.05). Further dynamic mechanical alterations were detected in hysteresis, phase shift, and dynamic modulus. Shear moduli correlated negatively with lamellar thickness (G1: r_s = −0.63, G2: r_s = −0.71).

Conclusions

There were significant alterations in AF shear moduli and dynamic properties in DD individuals when compared to non-DD controls. Structural correlations highlight the role of the highly organized AF lamellar structure on shear modulus values. These findings suggest that altered AF mechanics may contribute to DD pathology and associated low back pain, warranting further investigation into structural and functional AF changes in symptomatic individuals.

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与非手术对照组相比，疼痛性椎间盘退变患者纤维外环剪切模量降低和板层形态改变。

背景：脊柱和椎间盘（IVD）完整性的稳定性是由高度组织化的纤维软骨环（AF）实现的。AF的剪切特性对于维持IVD的完整性非常重要。AF剪切力学在退行性椎间盘（DD）中仍未被充分研究，特别是在比较轻度退行性椎间盘（非DD）和有症状的DD个体时。本研究测量了手术DD和非DD对照个体的组织力学特性（AF简单剪切模量和动态剪切特性）并检查了组织结构（光学相干断层扫描（OCT））。方法：从非DD供体（N = 13）和DD手术个体（N = 30）中采集AF全组织样本。从每个样品上切下两个前外侧AF (OAF) 5 mm立方体，并在两个方向上进行剪切，径向（冠状面，G1）和周向（矢状面，G2）。组织进行静态剪切和动态剪切，最大剪切应变为10%。结果：与非DD组织相比，DD组织在径向（G1）（非DD: 83.0±41.3 kPa, DD: 24.1±23.7 kPa）和周向（G2）（非DD: 226.2±81.9 kPa, DD: 54.0±40.2 kPa）方向上的静态剪切模量显著降低（p s = -0.63, G2: rs = -0.71）。结论：与非DD对照组相比，DD个体AF剪切模量和动态特性有显著改变。结构相关性强调了高度组织化的AF层状结构对剪切模量值的作用。这些发现表明，房颤机制的改变可能导致DD病理和相关的腰痛，需要进一步研究有症状个体的房颤结构和功能变化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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