Human foot three-dimensional finite element of modeling and its biomechanical applications

Abstract

目的: 探讨建立足部三维有限元模型的方法,应用模型模拟分析研究鞋垫设计参数,不同软组织刚度和受力情况下对足部的生物力学影响。 方法: 建立基于解剖结构,包括软组织,韧带和腱膜,考虑材料的非线性和关节接触的足部三维有限元模型。有限元模型的可靠性利用模拟足踝关节在不同病理、手术和鞋垫矫治情况下的生物力学反应来验证。 结果: 有限元分析结果表明,定制型鞋垫的形状比鞋垫材料的刚度对减少足底最大压力有更重要影响。软组织刚度的增加引起足底接触面积的减小,从而会导致足底跖骨区最大压力增加。部分和完全松解足底腱膜都会降低足弓高度,并增加足底韧带的张力和增加中足和跖骨的应力。体重增加和跟腱拉力增加都将成倍足底筋膜的拉力。 结论: 所建足部有限元模型能预测足底压力分布和足内部骨骼软组织应力、应变情况,可以成为设计鞋垫和研究足部各种临床状况提供有力的分析工具。 Objective: To develop a three-dimensional (3D) comprehensive finite element (FE) foot model for studying the biomechanical effects of different parametrical designs with various foot orthoses, soft tissue stiffness and loading conditions. Methods: Based on the accurate anatomical structures including the encapsulated soft tissue, ligaments and plantar fascia, and taking the nonlinear properties of material and foot contacting into consideration, a 3D FE mode of foot was developed. The reliability and validity of the FE model to quantify the biomechanical response of the foot and ankle under different simulated pathological, surgical and orthotic conditions were investigated. Results: The FE analysis showed that such a custom-molded shape was more important for relieving of the plantar peak pressure than the stiffness of orthotic material as far as the design is concerned. Increasing soft tissue stiffness would lead to decrease the total contact area of the foot-support interface and then make the increases in plantar peak pressure of the bony prominences. Either reducing the stiffness of plantar fascia or surgical releases of the partial or the entire plantar fascia could decrease the arch height, increasing the strains of the plantar ligaments and intensifying the stresses in the midfoot and metatarsal bones. The FE predictions showed that both the increase of weight on the foot and achilles tendon loading resulted in an increase in tension of the plantar fascia with the latter showing a two-times larger straining effect. Conclusion: The established FE model, which allowed prediction of plantar pressure distributions as well as the internal stress and strain of the bony and soft tissue structures, can be an effective tool to study different clinical questions and for footwear design.