A simple measuring device for laboratory indentation tests on cartilage
A simple measuring device for laboratory indentation tests on cartilage
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DOI：
10.1515/bmt.2008.007
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发表时间：
2008-01-01
期刊：
影响因子：
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通讯作者：
Russlies, Martin
中科院分区：
文献类型：
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作者：
Koeller, Wolfgang;Kunow, Julius;Russlies, Martin
关节软骨和修复组织的力学测试能够判断它们承受机械载荷的能力。在过去，已经开发了不同的方法，需要复杂的技术设置和广泛的数据分析。因此，本项目的目的是建立一个简单的测量装置，用于实验室压痕试验。该装置包括一个增量式光学位移传感器，带有一个套筒轴承引导柱塞和一个抛光钢制成的球形尖端（半径：0.75或1.5 mm），一个敏感的测力传感器和一个刚性框架。压入力由柱塞的重力加上位移传感器内的弹簧力产生，水平为0.170 N或0.765 N。位移传感器通过测力传感器固定在框架上，测力传感器能够检测头端与组织的初始接触。称重传感器的标准不确定度为2 mN，位移传感器的标准不确定度为1 μ m。根据压痕蠕变试验，计算出“0.25-s弹性模量”。在薄橡胶片上进行测量以确定测量装置的质量。用这些橡胶片制成的圆柱体进行压缩试验，得到了与“0.25-s弹性模量”一致的对照数据，用羊股骨髁不同部位的软骨进行压痕试验，得到了非常好的重复性测量结果（± 7.5%）。
Mechanical testing of articular cartilage and repair tissue enables judgment of their capacity in withstanding mechanical loading. In the past, different methods have been developed requiring a complex technical setup and extensive data analysis. Therefore, the aim of the present project was to build up a simple measuring apparatus for laboratory indentation tests. The device consists of an incremental optical displacement transducer with a sleeve bearing guided plunger and a spherical tip made of polished steel (radius: 0.75 or 1.5 mm), a sensitive load cell and a stiff frame. The indentation force results from the plunger's gravity plus the force of the spring inside the displacement transducer and levels at 0.170 N or 0.765 N. The displacement transducer is fixed to the frame via the load cell that enables one to detect the initial contact of the tip with the tissue. The load cell has a standard uncertainty of 2 mN and the displacement transducer of 1 mu m. From indentation-creep tests, a "0.25-s elastic modulus" is calculated. Measurements on thin rubber sheets were carried out to determine the quality of the measuring device. Compression tests on cylinders made of these rubber sheets yielded control data, and a good agreement with the "0.25-s elastic modulus" was found. Indentation tests on cartilage at different sites of sheep femoral condyles yielded a very good repeatability of the measurement results (+/- 7.5%).