Schmidt Hendrik, Häussler Kim, Wilke Hans-Joachim, Wolfram Uwe
2 Julius Wolff Institut, Charité - Universitätsmedizin Berlin, Berlin - Germany.
J Appl Biomater Funct Mater. 2015 Mar 18;13(1):66-71. doi: 10.5301/jabfm.5000176.
The intervertebral disc (IVD) is a complex, flexible joint between adjacent vertebral bodies that provides load transmission while permitting movements of the spinal column. Finite element models can be used to help clarify why and how IVDs fail or degenerate. To do so, it is of importance to validate those models against controllable experiments. Due to missing experimental data, shear properties are not used thus far in validating finite element models. This study aimed to investigate the structural shear properties of human lumbar IVDs in posteroanterior (PA) and laterolateral (LL) loading directions.
Fourteen lumbar IVDs (median age: 49 years) underwent direct shear in PA and LL loading directions. A custom-build shear device was used in combination with a materials testing machine to load the specimens until failure. Shear stiffness, ultimate shear force and displacement, and work to failure were determined.
Each specimen was tested until complete or partial disruption. Median stiffness in PA direction was 490 N/mm and in LL direction 568 N/mm. Median ultimate shear force in the PA direction was 2,877 N and in the LL direction 3,199 N. Work to failure was 12 Nm in the PA and 9 Nm in the LL direction.
This study was an experiment to subject IVDs to direct shear. The results could help us to understand the structure and function of IVDs with regard to mechanical spinal stability, and they can be used to validate finite element models of the IVD.
椎间盘（IVD）是相邻椎体之间的一个复杂、灵活的关节，在允许脊柱运动的同时提供载荷传递。有限元模型可用于帮助阐明IVD失效或退变的原因及方式。为此，依据可控实验对这些模型进行验证至关重要。由于缺少实验数据，目前在验证有限元模型时尚未使用剪切特性。本研究旨在探究人腰椎IVD在前后（PA）和后外侧（LL）加载方向上的结构剪切特性。
对14个腰椎IVD（中位年龄：49岁）进行PA和LL加载方向的直接剪切实验。使用定制的剪切装置与材料试验机相结合对标本进行加载直至破坏。测定剪切刚度、极限剪切力和位移以及破坏功。
每个标本均测试至完全或部分破坏。PA方向的中位刚度为490N/mm，LL方向为568N/mm。PA方向的中位极限剪切力为2877N，LL方向为3199N。PA方向的破坏功为12Nm，LL方向为9Nm。
本研究是一项对IVD进行直接剪切的实验。这些结果有助于我们了解IVD在脊柱机械稳定性方面的结构和功能，并且可用于验证IVD的有限元模型。
