Ledoux William R, Meaney David F, Hillstrom Howard J
Department of Veterans Affairs, RR&D Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle WA, 98108, USA.
J Biomech Eng. 2004 Dec;126(6):831-7. doi: 10.1115/1.1824133.
Little is known about the structural properties of plantar soft-tissue areas other than the heel; nor is it known whether the structural properties vary depending on location. Furthermore, although the quasi-linear viscoelastic (QLV) theory has been used to model many soft-tissue types, it has not been employed to model the plantar soft tissue. The structural properties of the plantar soft tissue were quantified via stress relaxation experiments at seven regions (subcalcaneal, five submetatarsal, and subhallucal) across eight cadaveric feet. The cadaveric feet were 36.9 +/- 17.4 (mean +/- S.D.) years of age, all free from vascular diseases and orthopedics disorders. All tests were performed at a constant environmental temperature of 35 degrees C. Stress relaxation experiments were performed; different loads were employed for different areas based on normative gait data. A modification of the relaxation spectrum employed within the QLV theory allowed for the inclusion of frequency-sensitive relaxation properties in addition to nonlinear elastic behavior. The tissue demonstrated frequency-dependent damping properties that made the QLV theory ill suited to model the relaxation. There was a significant difference between the elastic structural properties (A) of the subcalcaneal tissue and all other areas (p = 0.004), and a trend (p = 0.067) for the fifth submetatarsal to have less viscous damping (c1) than the subhallucal, or first, second, or third submetatarsal areas. Thus, the data demonstrate that the structural properties of the foot can vary across regions, but careful consideration must be given to the applied loads and the manner in which the loads were applied.
除了足跟外，人们对足底其他软组织区域的结构特性知之甚少；也不清楚其结构特性是否因位置而异。此外，尽管准线性粘弹性（QLV）理论已被用于模拟多种软组织类型，但尚未用于模拟足底软组织。通过对8具尸体足部的7个区域（跟骨下、5个跖骨下和拇趾下）进行应力松弛实验，对足底软组织的结构特性进行了量化。尸体足部的年龄为36.9±17.4（平均±标准差）岁，均无血管疾病和骨科疾病。所有测试均在35摄氏度的恒定环境温度下进行。进行了应力松弛实验；根据标准步态数据，对不同区域施加不同的负荷。对QLV理论中使用的松弛谱进行了修改，除了非线性弹性行为外，还考虑了频率敏感的松弛特性。该组织表现出频率依赖性阻尼特性，这使得QLV理论不太适合模拟松弛过程。跟骨下组织与所有其他区域的弹性结构特性（A）存在显著差异（p = 0.004），并且第五跖骨下区域的粘性阻尼（c1）有低于拇趾下、第一、第二或第三跖骨下区域的趋势（p = 0.067）。因此，数据表明足部的结构特性可能因区域而异，但必须仔细考虑所施加的负荷以及负荷的施加方式。
