Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong, China; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen, China.
Comput Biol Med. 2021 May;132:104355. doi: 10.1016/j.compbiomed.2021.104355. Epub 2021 Mar 26.
Different arch support heights of the customized foot orthosis could produce different effects on the internal biomechanics of the foot. However, quantitative evidence is scarce. Therefore, we aimed to investigate and quantify the influence of arch support heights on the internal foot biomechanics during walking stance.
We reconstructed a foot finite element model from a volunteer with flexible flatfoot. The model enabled a three-dimensional representation of the plantar fascia and its interactions with surrounding osteotendinous structures. The volunteer walked in foot orthosis with different arch heights (low, neutral, and high). Muscle forces during gaits were calculated by a multibody model and used to drive a foot finite element model. The foot contact pressures and plantar fascia strains in different regions were compared among the insole conditions at the first and second vertical ground reaction force (VGRF) peak and VGRF valley instants.
The results indicated that peak foot pressures decreased in balanced standing and second VGRF as the arch support height increased. However, peak midfoot pressures increased during all simulated instants. Meanwhile, high arch support decreased the plantar fascia loading by 5%-15.4% in proximal regions but increased in the middle and distal regions.
Although arch support could generally decrease the plantar foot pressure and plantar fascia loading, the excessive arch height may induce high midfoot pressure and loadings at the central portion of the plantar fascia. The consideration of fascia-soft tissue interaction in modeling could improve the prediction of plantar fascia strains towards design optimization for orthoses.
定制足矫形器的不同足弓支撑高度可能对足部内部生物力学产生不同的影响。然而，定量证据很少。因此，我们旨在研究和量化足弓支撑高度对步行时足部内部生物力学的影响。
我们从一位患有柔性平足症的志愿者身上重建了一个足部有限元模型。该模型能够对足底筋膜及其与周围骨腱结构的相互作用进行三维表示。志愿者在不同足弓高度（低、中和高）的足矫形器中行走。步态时的肌肉力通过多体模型计算，并用于驱动足部有限元模型。在第一次和第二次垂直地面反力（VGRF）峰值和 VGRF 谷瞬间，比较了不同鞋垫条件下不同区域的足底接触压力和足底筋膜应变。
结果表明，随着足弓支撑高度的增加，平衡站立和第二次 VGRF 时的峰值足部压力降低。然而，所有模拟瞬间的中足峰值压力都增加了。同时，高足弓支撑降低了近端区域 5%-15.4%的足底筋膜负荷，但在中、远端区域增加了负荷。
虽然足弓支撑通常可以降低足底足压和足底筋膜负荷，但过高的足弓高度可能会导致中足压力升高和足底筋膜中央部分的负荷增加。在建模中考虑筋膜-软组织相互作用可以提高对足底筋膜应变的预测，从而优化矫形器的设计。
