Optimization of Prosthetic Foot and Ankle Stiffness for Standing and Walking

 产品说明： 使用下肢假肢行走的人通常比身体健全的人行走效率低（沃茨等人，1976年），其稳定性受损，部分原因是其假体功能缺陷（Gard & Fatone，2004年）。身体健全的人的解剖学踝关节僵硬与步行速度相适应（汉森等人，2004）和站立（汉森和王，2010）。为下肢截肢者装配试图复制相应解剖学功能的假足和踝机构是期望的（汉森等人，2004 a，B，2007，2010）。我们先前证明，人工踝关节改善了经胫骨（膝下）截肢者的行走能力（Su等人，2008年、2009年、2010年）。在该研究中，研究对象显然更喜欢使用假体踝关节组件行走，但有几个人表示他们在站立时感到不稳定（Su等人，2010年）。随后对这些数据的分析表明，添加顺应性假体踝部单元显著减小了踝-足翻转形状的半径（Gard等人，2011），这会不利地影响站立稳定性和步态表现（Gard &奇尔德里斯，2001; Klodd等人，2010 a，B）。本研究的目的是确定如何系统地改变假肢脚龙骨刚度和假肢踝关节刚度影响站立和行走， 单侧经胫骨截肢者。本研究的具体目的是：1.确定假肢足和踝关节刚度的不同组合如何影响单侧经胫骨假肢使用者的步态生物力学。当受试者以不同的速度行走并具有不同的假足和踝关节刚度组合时，将收集运动学、动能和能量消耗数据。2.确定假足和踝关节刚度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。将使用一系列测试评价受试者的站立平衡，这些测试测量平衡受到干扰时的平衡和恢复稳定性。受试者还将接受问卷调查，以记录他们在使用不同的假肢脚-踝关节配置时对舒适度、用力和稳定性的感知。在行走过程中允许踝关节运动正常范围的柔顺性足踝机构预计会增加步态表现，但会降低站立稳定性。相反，僵硬的脚踝组合可能会最大限度地提高站立稳定性，但会降低步态表现。确定最佳的假足和踝关节刚度组合将需要在这两种活动的明显不同的目标之间进行折衷。增加了解不同的假肢脚踝关节刚度组合如何影响站立和行走能力，将有助于假肢专家选择合适的部件，鼓励开发具有自适应刚度的假肢脚踝关节机制，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.