Optimization of Prosthetic Foot and Ankle Stiffness for Standing and Walking

 说明： 使用假肢行走的人通常比健全的人行走效率低(Waters等人，1976)，而且他们的稳定性受到损害，部分原因是他们的假肢功能不足(Gard&Fatone，2004)。健全人的解剖踝关节僵硬与行走速度(Hansen et al.，2004)和站立(Hansen&Wang，2010)相适应。为截肢者安装试图复制相应解剖功能的假肢足和踝关节机制是可取的(Hansen等人，2004a，b，2007,2010)。我们先前证明了假肢踝关节改善了经胫骨(膝下)截肢者的行走能力(Su等人，2008、2009、2010)。在那项研究中，研究对象显然更喜欢使用假肢脚踝部件行走，但有几个人表示他们在站立时感觉不稳定(Su等人，2010年)。随后对这些数据的分析表明，添加顺应性假肢单元显著减小了踝足翻转形状的半径(Gard等人，2011年)，这会对站立稳定性和步态表现产生不利影响(Gard&Chilresse，2001；Klod等人，2010a，b)。这项研究的目的是确定系统地改变假肢足部龙骨僵硬和假肢踝关节僵硬对站立和行走的影响。 单侧、经胫骨截肢者。本研究的具体目的是：1.确定假足和踝关节僵硬的不同组合如何影响单侧胫骨假体使用者的步态生物力学。当受试者以不同的速度行走，并使用不同的假肢和脚踝僵硬组合时，运动学、运动学和能量消耗数据将被收集起来。2.确定假足和踝关节僵硬的不同组合如何影响单侧、经胫骨假体使用者的站立稳定性。受试者的站立平衡将通过一系列测试来评估，这些测试测量平衡和恢复稳定性，因为平衡被扰乱了。受试者还将接受问卷调查，以记录他们在使用不同的脚踝假肢配置时对舒适性、体力和稳定性的感受。在步行过程中，允许正常范围的踝关节运动的顺应性脚踝机构有望提高步态表现，但会降低站立稳定性。相反，僵硬的脚踝组合可能会使站立稳定性最大化，但会降低步态表现。确定最佳的假肢足和踝关节僵硬组合将需要在这两种活动明显不同的目标之间达成妥协。更多地了解不同的假肢脚踝僵硬组合如何影响站立和行走能力，将有助于假肢医生选择适当的部件，鼓励开发具有适应性僵硬的假肢脚踝机构，并最终提高假肢使用者的生活质量。

 DESCRIPTION: Persons who walk with lower-limb prostheses are generally less efficient ambulators than able-bodied individuals (Waters et al., 1976) and their stability is compromised, attributable in part t deficiencies in the function of their prostheses (Gard & Fatone, 2004). Anatomical ankle joint stiffness in able-bodied persons adapts with walking speed (Hansen et al., 2004) and for standing (Hansen & Wang, 2010). Fitting lower-limb amputees with prosthetic foot and ankle mechanisms that attempt to replicate corresponding anatomical functions is desirable (Hansen et al., 2004a,b, 2007, 2010). We previously demonstrated that prosthetic ankle joints improve walking performance in persons with transtibial (below-knee) amputation (Su et al., 2008, 2009, 2010). In that study, research subjects clearly preferred walking with the prosthetic ankle components, but several indicated that they felt unstable during standing (Su et al., 2010). Subsequent analyses of those data indicated that the addition of a compliant prosthetic ankle unit significantly reduced the radius of the ankle-foot roll-over shape (Gard et al., 2011), which can adversely affect standing stability and gait performance (Gard & Childress, 2001; Klodd et al., 2010a,b). The purpose of this investigation is to determine how systematically varying the prosthetic foot keel stiffness and prosthetic ankle joint stiffness affects standing and walking in persons with unilateral, transtibial amputations. The specific aims for this study are: 1. To determine how different combinations of prosthetic foot and ankle stiffness affect gait biomechanics of unilateral, transtibial prosthesis users. Kinematic, kinetic and energy expenditure data will be collected as subjects walk at different speeds and with different combinations of prosthetic foot and ankle stiffness. 2. To determine how different combinations of prosthetic foot and ankle stiffness affect standing stability of unilateral, transtibial prostheis users. Standing balance of subjects will be evaluated using a series of tests that measure balance and recovery stability as balance is perturbed. Subjects will also be administered questionnaires to document their perceptions of comfort, exertion and stability while using the different prosthetic foot-ankle configurations. Compliant foot-ankle mechanisms that allow for a normal range of ankle joint motion during walking are expected to increase gait performance, but decrease standing stability. Conversely, a rigid foot-ankle combination will likely maximize standing stability, but decrease gait performance. Determination of an optimal prosthetic foot and ankle stiffness combination will require a compromise between the apparent disparate objectives for these two activities. Increased understanding about how different prosthetic foot-ankle stiffness combinations affect standing and walking abilities will facilitate appropriate component selection by prosthetists, encourage development of prosthetic foot-ankle mechanisms with adaptable stiffness, and ultimately improve quality of life for prosthesis users.