Bovine annulus fibrosus hydration affects rate-dependent failure mechanics in tension
Bovine annulus fibrosus hydration affects rate-dependent failure mechanics in tension
复制标题
牛纤维环水合影响张力下的速率依赖性失效力学
DOI：
10.1016/j.jbiomech.2019.04.008
复制
发表时间：
2019
影响因子：
2.4
通讯作者：
O'Connell, Grace D.
中科院分区：
文献类型：
--
作者：
Werbner, Benjamin;Spack, Katherine;O'Connell, Grace D.
椎间盘的高含水量对其承载功能和粘弹性力学行为至关重要。与椎间盘退变相关的主要生化变化之一是蛋白聚糖的丢失，导致组织脱水。虽然以前的研究已经报道了体内变性对纤维环（AF）失效机制的影响，但水的独立作用仍然不清楚，组织的速率依赖性失效反应也是如此。我们的第一个目标是确定加载速率对AF在张力下失效特性的影响；我们的第二个目标是量化含水量对破坏特性的影响。通过酶解糖胺聚糖（GAGs）和渗透负荷改变了水的含量。牛AF样品沿周向以0.00697%/s或6.97%/s的速度单调测试直至失效。在所有处理组中，加载率的增加导致线性区域模量、破坏应力和应变能密度增加~ 50% （p < 0.001）。降低GAG和含水量导致模量、破坏应力和应变能密度降低；然而，这些差异仅在低加载速率下观察到（p < 0.05；在高加载速率下没有变化）。渗透负荷被用来评估水化的影响，独立于GAG组成，导致类似的水含量，模量和应变能密度的减少。这表明水合作用对于维持组织刚度和能量吸收能力至关重要，而不是强度，并且GAGs对组织强度的贡献独立于介导含水量。
The high water content of the intervertebral disc is essential to its load bearing function and viscoelastic mechanical behavior. One of the primary biochemical changes associated with disc degeneration is the loss of proteoglycans, which leads to tissue dehydration. While previous studies have reported the effects ofin vivodegeneration on annulus fibrosus (AF) failure mechanics, the independent role of water remains unclear, as does the tissue’s rate-dependent failure response. Our first objective was to determine the effect of loading rate on AF failure properties in tension; our second objective was to quantify the effect of water content on failure properties. Water content was altered through enzymatic digestion of glycosaminoglycans (GAGs) and through osmotic loading. Bovine AF specimens were tested monotonically to failure along the circumferential direction at 0.00697%/s or 6.97%/s. Increased loading rate resulted in a ∼50% increase in linear-region modulus, failure stress, and strain energy density across all treatment groups (p < 0.001). Decreased GAG and water contents resulted in decreased modulus, failure stress, and strain energy density; however, these differences were only observed at the low loading rate (p < 0.05; no changes at high rate). Osmotic loading was used to evaluate the effect of hydration independently from GAG composition, resulting in similar decreases in water content, modulus, and strain energy density. This suggests that hydration is essential for maintaining tissue stiffness and energy absorption capacity, rather than strength, and that GAGs contribute to tissue strength independently from mediating water content.