Jurvelin J S, Räsänen T, Kolmonen P, Lyyra T
Department of Anatomy, University of Kuopio, Finland.
J Biomech. 1995 Feb;28(2):231-5. doi: 10.1016/0021-9290(94)00060-h.
Analysis of the mechanical properties of articular cartilage necessitates determination of thickness of the tested tissue. To evaluate the suitability of different methods for thickness measurements, the thickness of bovine and canine knee articular cartilage was determined with optical (stereomicroscopic), needle probe and ultrasonic techniques. The results obtained with the stereomicroscope and the needle probe showed high, linear correlations (r = 0.97, n = 80). The mean thickness obtained with the needle was slightly higher than the optical thickness (0.88 +/- 0.36 mm vs 0.85 +/- 0.34 mm, mean +/- S.D., n = 80, p < 0.01, matched-pairs Student t-test) or the ultrasonic thickness (0.93 +/- 0.42 mm vs 0.87 +/- 0.36 mm, n = 45, p < 0.05). The high scatter between optical and ultrasonic thickness, considered to be due to complex measurement geometry of canine knee articular cartilage, invalidated the use of the A-mode, 10 MHz-ultrasonic device for thickness measurements. Based on the results of uncertainty analysis it is concluded that optical and needle probe methods can be used interchangeably when determining shear modulus of articular cartilage with indentation tests. However, if high area-aspect ratios (indenter radius-to-cartilage thickness ratios) are used in the indentation measurements uncertainty in shear modulus may be markedly increased due to possible errors in the measurement of cartilage thickness.
分析关节软骨的力学性能需要测定受试组织的厚度。为评估不同厚度测量方法的适用性，采用光学（立体显微镜）、针式探头和超声技术测定了牛和犬膝关节软骨的厚度。立体显微镜和针式探头测得的结果显示出高度的线性相关性（r = 0.97，n = 80）。针式探头测得的平均厚度略高于光学测量的厚度（0.88±0.36毫米对0.85±0.34毫米，平均值±标准差，n = 80，p < 0.01，配对学生t检验）或超声测量的厚度（0.93±0.42毫米对0.87±0.36毫米，n = 45，p < 0.05）。光学测量厚度与超声测量厚度之间的高度离散，被认为是由于犬膝关节软骨复杂的测量几何形状所致，这使得使用A模式10兆赫超声设备进行厚度测量无效。基于不确定度分析的结果得出结论，在通过压痕试验测定关节软骨的剪切模量时，光学和针式探头方法可以互换使用。然而，如果在压痕测量中使用高面积-纵横比（压头半径与软骨厚度之比），由于软骨厚度测量中可能存在的误差，剪切模量的不确定度可能会显著增加。
