Wearing Scott C, Smeathers James E, Yates Bede, Urry Stephen R, Dubois Philip
Health QWest and Bioengineering Unit, University of Strathclyde, 106 Rottenrow, Glasgow, Scotland G40NW, UK.
Clin Biomech (Bristol). 2009 May;24(4):397-402. doi: 10.1016/j.clinbiomech.2009.01.002. Epub 2009 Feb 15.
Altered mechanical properties of the heel pad have been implicated in the development of plantar heel pain. However, the in vivo properties of the heel pad during gait remain largely unexplored in this cohort. The aim of the current study was to characterise the bulk compressive properties of the heel pad in individuals with and without plantar heel pain while walking.
The sagittal thickness and axial compressive strain of the heel pad were estimated in vivo from dynamic lateral foot radiographs acquired from nine subjects with unilateral plantar heel pain and an equivalent number of matched controls, while walking at their preferred speed. Compressive stress was derived from simultaneously acquired plantar pressure data. Principal viscoelastic parameters of the heel pad, including peak strain, secant modulus and energy dissipation (hysteresis), were estimated from subsequent stress-strain curves.
There was no significant difference in loaded and unloaded heel pad thickness, peak stress, peak strain, or secant and tangent modulus in subjects with and without heel pain. However, the fat pad of symptomatic feet had a significantly lower energy dissipation ratio (0.55+/-0.17 vs. 0.69+/-0.08) when compared to asymptomatic feet (P<.05).
Plantar heel pain is characterised by reduced energy dissipation ratio of the heel pad when measured in vivo and under physiologically relevant strain rates.
足跟垫力学性能的改变与足底足跟痛的发生有关。然而，该队列中足跟垫在步态过程中的体内特性仍 largely 未被探索。本研究的目的是描述有和没有足底足跟痛的个体在行走时足跟垫的整体压缩特性。
从九名单侧足底足跟痛的受试者和同等数量的匹配对照在以其偏好速度行走时获取的动态侧位足部 X 光片中，在体内估计足跟垫的矢状厚度和轴向压缩应变。压缩应力从同时获取的足底压力数据得出。足跟垫的主要粘弹性参数，包括峰值应变、割线模量和能量耗散（滞后），从随后的应力 - 应变曲线估计。
有和没有足跟痛的受试者在加载和卸载时足跟垫厚度、峰值应力、峰值应变或割线和切线模量方面没有显著差异。然而，与无症状的脚相比，有症状的脚的脂肪垫能量耗散率显著更低（0.55±0.17 对 0.69±0.08）（P<0.05）。
在体内且在生理相关应变率下测量时，足底足跟痛的特征是足跟垫能量耗散率降低。
