Effect of loading history on material properties of human heel pad: an in-vivo pilot investigation during gait.
Effect of loading history on material properties of human heel pad: an in-vivo pilot investigation during gait.
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负载历史对人体足跟垫材料特性的影响：步态期间的体内试验研究
DOI：
10.1186/s12891-022-05197-w
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发表时间：
2022-03-15
影响因子：
2.3
通讯作者：
Ma X
中科院分区：
文献类型：
--
作者：
Teng ZL;Yang XG;Geng X;Gu YJ;Huang R;Chen WM;Wang C;Chen L;Zhang C;Helili M;Huang JZ;Wang X;Ma X
本研究旨在开发一种新的动态测量技术，用于测试材料性能，并研究在实际步态中持续压缩载荷对人体后跟垫结构和力学性能的影响。采用双透视成像系统（DFIS）和动态脚踏接触试压板测量材料在零时刻和连续加载后的原始厚度、峰值应变、峰值应力、弹性模量、粘性模量和能量耗散率（EDR）。纳入健康受试者10例，年龄23 ~ 72岁，平均46.5±17.6岁。对所有受试者进行“三步步态循环”，第二步用脚后跟敲打测力板上的标记位置，以保持测试足的位置在透视镜的视野内。受试者在放松（零时间组）和疲劳（持续负荷组）状态下进行测量，使用相同的程序测量左、右脚跟。连续加载前后的峰值应变、峰值应力、弹性模量和EDR相似，而粘性模量（中位数：43.9 vs. 20.37 kPa•s, p < 0.001）和初级厚度（中位数：15.99 vs. 15.72 mm, p < 0.001）显著降低。年龄被证明与零时间（R = -0.507）和连续载荷（R = -0.607）的原始厚度适度相关。峰值应力与弹性模量在连续加载前（R = 0.741）和连续加载后（R = 0.802）呈显著相关。峰值应变与连续加载前（R = -0.765）和连续加载后（R = -0.801）的弹性模量相关。黏性模量与峰值应力/峰值应变的相关关系与上表相似（R分别为0.643、0.577、−0.586、−0.717）。连续加载前（R = 0.821）和连续加载后（R = 0.784）黏性模量与弹性模量呈正相关。通过动态透视结合足底压力板，可以获得足跟垫在实际步态中的体内粘弹性等数据。年龄与鞋垫原始厚度和峰值应变呈负相关，与黏性模量呈正相关。重复加载会降低跟垫的初级厚度和粘滞模量。
This study was aimed to develop a novel dynamic measurement technique for testing the material properties and investigating the effect of continuous compression load on the structural and mechanical properties of human heel pad during actual gait. The dual fluoroscopic imaging system (DFIS) and dynamic foot-ground contact pressure-test plate were used for measuring the material properties, including primary thickness, peak strain, peak stress, elastic modulus, viscous modulus and energy dissipation rate (EDR), both at time zero and following continuous loading. Ten healthy pilot subjects, aged from 23 to 72 (average: 46.5 ± 17.6), were enrolled. A “three-step gait cycle” is performed for all subjects, with the second step striking at a marked position on the force plate with the heel to maintain the location of the tested foot to be in the view of fluoroscopes. The subjects were measured at both relaxed (time-zero group) and fatigue (continuous-loading group) statuses, and the left and right heels were measured using the identical procedures. The peak strain, peak stress, elastic modulus, and EDR are similar before and after continuous load, while the viscous modulus was significantly decreased (median: 43.9 vs. 20.37 kPa•s; p < 0.001) as well as primary thicknesses (median: 15.99 vs. 15.72 mm; p < 0.001). Age is demonstrated to be moderately correlated with the primary thicknesses both at time zero (R = -0.507) and following continuous load (R = -0.607). The peak stress was significantly correlated with the elastic modulus before (R = 0.741) and after continuous load (R = 0.802). The peak strain was correlated with the elastic modulus before (R = -0.765) and after continuous load (R = -0.801). The correlations between the viscous modulus and peak stress/ peak strain are similar to above(R = 0.643, 0.577, − 0.586 and − 0.717 respectively). The viscous modulus is positively correlated with the elastic modulus before (R = 0.821) and after continuous load (R = 0.784). By using dynamic fluoroscopy combined with the plantar pressure plate, the in vivo viscoelastic properties and other data of the heel pad in the actual gait can be obtained. Age was negatively correlated with the primary thickness of heel pad and peak strain, and was positively correlated with viscous modulus. Repetitive loading could decrease the primary thickness of heel pad and viscous modulus.