Bonnet Xavier, Pillet Hélenè, Fodé Pascale, Lavaste Francois, Skalli Wafa
Arts et Metiers ParisTech, Laboratoire de Biomecanique, 151 bd de l'hôpital 75013 Paris, France.
Proc Inst Mech Eng H. 2012 Jan;226(1):70-5. doi: 10.1177/0954411911429534.
Energy-storing prosthetic feet are designed to store energy during mid-stance motion and to recover it during late-stance motion. Gait analysis is the most commonly used method to characterize prosthetic foot behaviour during walking. In using this method, however, the foot is generally modelled as a rigid body. Therefore, it does not take into account the ability of the foot to deform. However, the way this deformation occurs is a key parameter of various foot properties under gait conditions. The purpose of this study is to combine finite element modelling and gait analysis in order to calculate the strain, stress and energy stored in the foot along the stance phase for self-selected and fast walking speeds. A finite element model, validated using mechanical testing, is used with boundary conditions collected experimentally from the gait analysis of a single transtibial amputee. The stress, strain and energy stored in the foot are assessed throughout the stance phase for two walking speed conditions: a self-selected walking speed (SSWS), and a fast walking speed (FWS). The first maximum in the strain energy occurs during heel loading and reaches 3J for SSWS and 7J for FWS at the end of the first double support phase. The second maximum appears at the end of the single support phase, reaching 15J for SSWS and 18J for FWS. Finite element modelling combined with gait analysis allows the calculation of parameters that are not obtainable using gait analysis alone. This modelling can be used in the process of prosthetic feet design to assess the behaviour of a prosthetic foot under specific gait conditions.
储能假脚旨在在支撑中期运动时储存能量，并在支撑后期运动时恢复能量。步态分析是表征步行过程中假脚行为最常用的方法。然而，在使用这种方法时，假脚通常被建模为刚体。因此，它没有考虑到假脚变形的能力。然而，这种变形发生的方式是步态条件下各种脚部特性的关键参数。本研究的目的是将有限元建模与步态分析相结合，以便计算在自选和快速步行速度下，整个支撑阶段假脚中储存的应变、应力和能量。使用机械测试验证的有限元模型与从一名单小腿截肢者的步态分析中实验收集的边界条件一起使用。在两种步行速度条件下，即自选步行速度（SSWS）和快速步行速度（FWS）下，评估整个支撑阶段假脚中储存的应力、应变和能量。应变能的第一个最大值出现在足跟加载期间，在第一个双支撑阶段结束时，自选步行速度下达到3焦耳，快速步行速度下达到7焦耳。第二个最大值出现在单支撑阶段结束时，自选步行速度下达到15焦耳，快速步行速度下达到18焦耳。有限元建模与步态分析相结合，可以计算出仅使用步态分析无法获得的参数。这种建模可用于假脚设计过程中，以评估特定步态条件下假脚的行为。
