Effect of Prosthetic Foot-Ankle Stiffness on Amputee Function

描述（由申请人提供）： 许多下肢截肢者戴着假脚，通过弹性龙骨的关节储存和释放能量。这些能量储存和返回（ESAR）脚的功能是提供机械能，用于曾经由穿过踝关节的肌肉提供的推进。临床医生非常清楚，足部僵硬强烈影响截肢者步态的力学，并根据体重和自我报告的活动水平，规定ESAR足部具有患者识别的僵硬水平。然而，存在非常少的客观生物力学数据来指导一个刚度水平与另一个刚度水平的处方，并且截肢者相对于非截肢者继续经历显著的生物力学和代谢步态缺陷，并且由于异常肢体负荷，在完整肢体和残肢中经常发生继发性肌肉骨骼疾病。我们相信，如果了解截肢者的ESAR特性与生物力学和代谢反应之间的关系，许多这些不良结果可以得到缓解。然而，迄今为止，没有研究系统地改变假足刚度在很大范围内的价值，以确定这些关系。另一个影响因素是，迄今为止，大多数评估ESAR足部有效性的研究都是在直线行走期间进行的。然而，非矢状面活动（如转动）在日常生活中很普遍，并为ESAR足部创建了一组不同的设计要求，尚未进行评估。为了解决这一重要的临床问题，本研究的总体目标是进行一项系统的研究，在直线行走和转弯过程中，假肢足踝刚度对截肢者步态性能的影响，以定义这种关系，并探索其作为预测处方工具的用途。一个独特的元素，拟议的工作是使用一个快速原型系统，以快速制造病人特定的假肢脚与广泛的刚度特性。具体目标1将通过单侧经胫骨截肢者（n=20）在直线行走过程中佩戴具有5种不同刚度水平的假足的人类受试者实验，确定矢状面足刚度对截肢者步态的影响。我们将使用快速成型技术来制造与每个受试者自己的临床处方假体和其他四个（125%和150%或多或少的刚度）的矢状面和冠状面刚度特性相匹配的脚。将使用机器人步态模拟器精确确定每只脚的患者特定属性。在对僵硬条件设盲的情况下，每名受试者将在假体上直线行走，以测试将矢状面僵硬与步态力学和代谢成本的预期变化相关的特定假设。具体目标2将使用类似的实验设计和方法确定冠状面足部僵硬对截肢者步态的影响。单侧经胫骨截肢者（n=20）将在直线行走和沿着曲线路径行走时佩戴具有五种不同冠状面刚度水平（按规定和125%和150%或多或少刚度）的假足，第二个实验的数据将使假设检验能够将冠状面刚度与步态力学的预期变化联系起来。我们假设截肢者的活动性可以通过优化他们的假足在矢状面和冠状面的刚度来改善。这项研究将提供一个全面的了解如何假肢足性能影响截肢者步态，并帮助我们实现我们的长期目标，开发预测处方工具的诊所，将导致更大的截肢者的流动性，独立性和生活质量。

DESCRIPTION (provided by applicant): Project Summary Many lower limb amputees wear prosthetic feet that store and release energy through articulation of an elastic keel. The function of these energy storage and return (ESAR) feet are to provide mechanical energy for propulsion that was once provided by the muscles crossing the ankle joint. Clinicians are well aware that foot stiffness strongly influences the mechanics of amputee gait and prescribe ESAR feet with manufacturer-identified stiffness levels based on body weight and self-reported activity level. However, very little objective biomechanical data exists to guide the prescription of one stiffness level versus another and amputees continue to experience significant biomechanical and metabolic gait deficits relative to non-amputees and often develop secondary musculoskeletal disorders in both the intact and residual limbs due to abnormal limb loading. We believe many of these adverse results can be mitigated if the relationships between ESAR properties and the biomechanical and metabolic response of amputees are understood. However, to date no study has systematically varied prosthetic foot stiffness across a wide range of values to identify these relationships. Another contributing factor is that to date the majority of research evaluating the effectiveness of ESAR feet has been performed during straight line walking. However, non-sagittal plane activities such as turning are prevalent in daily living and create a different set of design requirements for ESAR feet that has yet to be evaluated. To address this important clinical problem, the overall goal of this research is to perform a systematic study of the influence of prosthetic foot-ankle stiffness on amputee gait performance during straight-line walking and turning to define this relationship and explore its use as a predictive prescription tool.. A unique element of the proposed work is the use of a rapid prototyping system to quickly fabricate patient- specific prosthetic feet with a wide range of stiffness properties. Specific Aim 1 will identify the effects of sagittal plane foot stiffness on amputee gait through a human subject experiment with unilateral transtibial amputees (n=20) wearing prosthetic feet with five different stiffness levels during straight-line walking. We will use rapid prototyping techniques to fabricate feet that match the stiffness properties in both the sagittal and coronal planes of each subject's own clinically prescribed prosthesis and four others (125% and 150% more or less stiff). The patient-specific properties of each foot will be precisely determined using a robotic gait simulator. Blinded to stiffness conditions, each subject will walk in a straight line on the prostheses to test specific hypotheses relating sagittal plane stiffness to expected changes in gait mechanics and metabolic cost. Specific Aim 2 will identify the effects of coronal plane foot stiffness on amputee gait using a similar experimental design and methods. Unilateral transtibial amputees (n=20) will wear prosthetic feet with five different coronal plane stiffness levels (as-prescribed and 125% and 150% more or less stiff) during straight-line walking and while walking along a curved path. Data from this second experiment will enable hypothesis testing relating coronal plane stiffness to expected changes in gait mechanics. We hypothesize that amputee mobility can be improved by optimizing the stiffness of their prosthetic feet in both the sagittal and coronal planes. This study will provide a thorough understanding of how prosthetic foot properties effect amputee gait and help us achieve our long-term goal of developing predictive prescription tools for the clinic that will result in greater amputee mobility, independence, and quality of life.