不同病理学等级关节炎软骨的三相力学特性

目的基于超声膨胀观测技术与三相理论提取关节软骨的轴向弹性模量,探索不同等级关节炎软骨的三相力学特性。方法对不同阶段的兔子关节炎软骨样本进行病理学分级,基于高频瞬态超声测量技术获取软骨因自由膨胀引起的组织应变量,结合组织的固定电荷密度和水体积分数,运用三相模型估计软骨的轴向弹性模量,并进行相关性分析。结果正常软骨与关节炎软骨的轴向弹性模量存在着明显差异(P<0.05),不同等级软骨样本的轴向弹性模量存在明显差异(P<0.05)。正常软骨组织的平均弹性模量为(15.87±6.30)MPa,随着关节炎的发生与关节炎程度的加重,软骨的弹性模量逐渐减小,1、2、3级软骨样本的轴向弹性模量分别为(11.33±5.21)、(9.15±5.68)、(6.05±4.99)MPa。结论不同病理学关节炎等级软骨样本的三相力学特性有明显差异,该研究为应用软骨组织的力学属性定量评判关节炎的严重程度提供了新的思路。

Triphasic mechanical properties of osteoarthritis cartilage with different pathological grades

Objective To obtain the axial elastic modulus of rabbit articular cartilage based on the ultrasound swelling observation technique and the triphasic theory, and to explore the triphasic mechanical properties of the osteoarthritis cartilage with different pathological grades. Methods The articular cartilage samples from rabbit knees were assessed according to the different pathological grades. The swelling strains were recorded based on the high frequency transient ultrasound measurement technique. The axial elastic modulus of the cartilage samples was extracted based on the fixed charge density, the water volume fraction and the triphasic model. Correlation analysis was also made. Results There were both significant differences in axial elastic modulus between the normal cartilages and among the osteoarthritis cartilage with different pathological grades (P<0.05). The value of axial elastic modulus decreased with the increase of osteoarthritis grades. For normal cartilage samples, the average axial elastic modulus was (15.87±6.30) MPa. For osteoarthritis cartilages of grade 1, 2 and 3, the value of axial elastic modulus were (11.33±5.21), (9.15±5.68) and (6.05±4.99) MPa, respectively. Conclusions This study showed there are significant differences in triphasic mechanical properties of the articular cartilage with different osteoarthritis grades, which may provide some new thought for the quantitative assessment of osteoarthritis grade based on mechanical properties of cartilage.