Ebara S, Iatridis J C, Setton L A, Foster R J, Mow V C, Weidenbaum M
Department of Orthopaedic Surgery, Osaka University Medical School, Japan.
Spine (Phila Pa 1976). 1996 Feb 15;21(4):452-61. doi: 10.1097/00007632-199602150-00009.
The in vitro tensile behavior of multiple-layer samples of anulus fibrosus were investigated from nondegenerate intervertebral discs.
To quantify the intrinsic tensile behavior of nondegenerate anulus fibrosus and the variations with position and age in the intervertebral disc.
Tension is an important loading mode in the anulus fibrosus. The tensile behavior of single- and multiple-layer samples of anulus fibrosus has been shown to vary with specimen orientation, position in the disc, and environmental conditions. Little is known of the changes in these site-specific tensile properties of the anulus with aging or degeneration of the intervertebral disc.
Multiple-layer specimens of anulus fibrosus were harvested with an orientation parallel to the circumference of the disc. Constant strain rate and uniaxial tensile tests were performed in 0.15 mol/l NaCl at slow strain rates to measure the intrinsic properties of the collagen-proteoglycan matrix of the anulus fibrosus. The tensile modulus, failure stress, failure strain, and strain energy density were determined. Statistical analyses were done to evaluate regional and age-related differences in these properties.
Significant radial and circumferential variations in the intrinsic tensile properties of anular samples were detected. The anterior anulus fibrosus had larger values for tensile moduli and failure stresses than the posterolateral anulus. Also, the outer regions of the anulus had greater moduli and failure stresses and lower failure strains than the inner regions. Strain energy density did not vary significantly with region. Significant, but very weak, correlations were detected between tensile properties and age of the intervertebral disc.
The observed variations in tensile behavior of multiple-layer anulus samples indicate that larger variations in tensile modulus and failure properties occur with radial position in the disc than from anterior to posterolateral regions. This pattern is likely related to site-specific variations in the tensile properties of the single-layer samples of anulus fibrosus lamellae and the organization of successive lamellae and their interactions. The results of the present study suggest that factors other than age, such as compositional and structural variations in the disc, are the most important determinants of tensile behavior of the anulus fibrosus.
对取自非退变椎间盘的纤维环多层样本进行体外拉伸行为研究。
量化非退变纤维环的固有拉伸行为以及椎间盘内随位置和年龄的变化情况。
张力是纤维环的一种重要加载模式。已表明纤维环单层和多层样本的拉伸行为会因样本方向、在椎间盘中的位置以及环境条件而有所不同。对于随着椎间盘老化或退变，纤维环这些特定部位拉伸特性的变化了解甚少。
以平行于椎间盘圆周的方向获取纤维环多层样本。在0.15 mol/l氯化钠溶液中以慢应变速率进行恒应变速率单轴拉伸试验，以测量纤维环胶原 - 蛋白聚糖基质的固有特性。测定拉伸模量、破坏应力、破坏应变和应变能密度。进行统计分析以评估这些特性的区域差异和与年龄相关的差异。
检测到环状样本固有拉伸特性存在显著的径向和周向变化。前侧纤维环比后外侧纤维环具有更大的拉伸模量和破坏应力值。此外，纤维环外层区域比内层区域具有更大的模量和破坏应力以及更低的破坏应变。应变能密度在各区域之间无显著差异。在拉伸特性与椎间盘年龄之间检测到显著但非常微弱的相关性。
观察到的纤维环多层样本拉伸行为变化表明，与从椎间盘前侧到后外侧区域相比，拉伸模量和破坏特性随椎间盘径向位置的变化更大。这种模式可能与纤维环薄片单层样本拉伸特性的特定部位变化、连续薄片的组织结构及其相互作用有关。本研究结果表明，除年龄外的其他因素，如椎间盘中成分和结构的变化，是纤维环拉伸行为的最重要决定因素。
