Large residual strains are present in the intervertebral disc annulus fibrosus in the unloaded state
Large residual strains are present in the intervertebral disc annulus fibrosus in the unloaded state
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DOI：
10.1016/j.jbiomech.2012.01.042
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发表时间：
2012-04-30
影响因子：
2.4
通讯作者：
Iatridis, J. C.
中科院分区：
文献类型：
--
作者：
Michalek, A. J.;Gardner-Morse, M. G.;Iatridis, J. C.
椎间盘纤维环（AF）在轴向压缩下受到髓核加压引起的高周向拉伸应力。在其他含有压力的组织中，如血管壁，在没有加压的情况下，沿组织内表面的残余压应力降低了加压下的峰值拉应力。本研究假设纤维环中存在类似的残余应力模式。残余应力的准确表征对于将非线性材料描述纳入圆盘模型以及设计有效的环空修复策略都是必不可少的。通过对切开释放残余应力前后的9个牛尾盘进行成像，我们测量到内部AF的平均残余拉伸为0.86 +/- 0.13，外部AF的平均残余拉伸为1.02 +/- 0.08。这些拉伸值用于计算内部AF的残余应力梯度，范围从-230 +/- 22 kPa的压缩到外部AF的54 +/- 0.2 kPa的张力。AF的材料模型假设AF在没有外部载荷时处于无应力参考状态。然而，本研究表明，即使没有外部载荷，AF中也存在较大的残余应力。通过突出、针注射或切口释放AF外部残余张力使闭合困难，并可能加速周围组织的退变。保留这些残余应力可能对维持椎间盘的机械功能和产生可行的心房颤动修复技术至关重要。(C) 2012 Elsevier Ltd.版权所有，
The intervertebral disc annulus fibrosus (AF) is subjected to high circumferential tensile stresses resulting from nucleus pulposus pressurisation under axial compression. In other pressure containing tissues, such as blood vessel walls, residual compressive stresses along the inside surface of the tissues without pressurisation reduce peak tensile stresses under pressurisation. This study hypothesised that similar patterns of residual stress exist in the annulus fibrosus. Accurate characterisation of residual stresses is essential for both the incorporation of nonlinear material descriptions into models of the disc as well as the design of effective annulus repair strategies. By imaging nine bovine caudal discs before and after the release of residual stresses via incision, we measured a mean residual stretch of 0.86 +/- 0.13 at the inner AF and 1.02 +/- 0.08 at the outer AF. These stretch values were used to calculate a gradient of residual stress ranging from -230 +/- 22 kPa of compression at the inner AF to 54 +/- 0.2 kPa of tension at the outer AF. Material models of AF have assumed that the AF was in a stress free reference state when there are no external loads. However, this study documents that there are large residual stresses in the AF even without external loads. The release of residual tension in the outer AF by herniation, needle injection or incisions makes closure difficult and may accelerate degeneration of the surrounding tissue. Retention of these residual stresses may be essential to maintaining disc mechanical function and to producing viable AF repair techniques. (C) 2012 Elsevier Ltd. All rights reserved,