Bio-Inspired Ankle-Knee Coupling to Enhance Walking for Individuals with Transtibial Amputation

尽管假足技术在过去十年中取得了进步，但越来越多的证据表明，根据假足与腿部的连接方式，下肢截肢(ILLA)患者仍处于身体劣势。伊拉的假肢踝关节和生物膝关节之间缺少物理连接。对于非截肢者，这种脚踝-膝盖连接是由腓肠肌(小腿)提供的，它帮助人将力量从脚踝转移到身体的其他部位。但这一重要的连接机制在经胫骨截肢过程中被切断，这可能会阻止Illa‘s能够有效地使用假肢提供的动力。这迫使Illa‘s改变步态，这可能会增加他们患上二次健康损害的风险，如慢性背痛和膝骨性关节炎。这项研究的目的是测试用人造腓肠肌恢复踝膝连接是否会改善能量从假体转移到身体的方式，从而改善Illa的健康和活动效果。首先，这项研究将专注于确定最佳的人造腓肠肌性能，用于被动(碳纤维)和动力(机动)假肢。接下来，研究人员将比较使用人造腓肠肌和不使用人造腓肠肌的情况。在研究的这一部分，将使用生物力学测量来评估益处。拟议的人造腓肠肌设计将是轻便的，舒适地适合在衣服下面，这样它可以很容易地与现有的假肢整合在一起，从而广泛地影响Illa的健康和移动性。这些改善的结果可能有助于减少继发性健康合并症，这些合并症在美国每年导致80亿美元的截肢相关医疗费用。研究团队汇集了生物力学、假体设计和临床护理方面的跨学科专业知识，学生将参与这项研究的所有阶段。这项建议的具体目标是(A)描述腓肠肌样的脚踝-膝关节耦合动力学对人类行走的影响，然后(B)检验这样的假设，即对于经胫骨截肢的个体来说，恢复这种耦合将改善他们的步态对称性和经济性，同时还可以减少不健康的关节负荷。案例研究数据、外骨骼实验和步行模拟提供了初步证据，表明恢复这种踝-膝耦合可能对Illa‘s有益；然而，这还没有经过实验测试，目前尚不清楚单个踝-膝耦合行为如何影响步态，或者哪种行为是最佳的。这项研究结合了各种测量方式，系统地评估了Illa在一系列踝关节-膝关节耦合行为下行走的生物力学和移动性结果，然后比较了使用和不使用优化的人工腓肠肌的步行效果。人工腓肠肌将使用可编程的非机载假体仿真器进行控制。这项研究将产生新的生物力学数据，为深入了解踝关节-膝关节耦合在两足步行中的功能益处以及这些动力学如何促进踝关节的力量转移提供洞察。将与临床合作伙伴一起进行一项可行性研究，以评估添加人造腓肠肌是否会改善ILLA患者在被动和动力足假体行走时与健康和活动相关的结果。这种方法是创新的，因为它寻求通过关注与身体的传输/接口来改善所有假肢的功能，而不仅仅是假足本身。通过提高行走能力，这项研究旨在改善Illa的行动能力和体力活动结果。

Despite advances in prosthetic foot technology over the last decade, there is growing evidence that individuals with lower-limb amputation (ILLA) are still at a physical disadvantage based on how a prosthetic foot is attached to its leg. ILLA's are missing a physical coupling between their prosthetic ankle and biological knee joint. In non-amputees, this ankle-knee coupling is provided by the gastrocnemius (calf) muscle, which helps a person to transfer power from their ankle to the rest of their body. But this important coupling mechanism is cut during transtibial amputation, which may prevent ILLA's from being able to effectively use power provided by their prosthetic foot. This then forces ILLA's to change their gait in such a way that it may increase their risk of secondary health impairments, like chronic back pain and knee osteoarthritis. The purpose of this research is to test if restoring ankle-knee coupling with an artificial gastrocnemius will improve the way power is transferred from the prosthesis to the body, and thereby improve health and mobility outcomes for ILLA's. First, this study will focus on identifying optimal artificial gastrocnemius properties, for use with both passive (carbon fiber) and powered (motorized) prosthetic feet. Next, the researchers will compare ILLA walking with vs. without the artificial gastrocnemius. During this portion of the study, biomechanical measurements will be used to assess benefits. The proposed artificial gastrocnemius design will be lightweight and comfortably fit underneath clothing, such that it can be easily integrated with existing prosthetic feet to broadly impact the health and mobility of ILLA. These improved outcomes may then help to reduce secondary health comorbidities that contribute to $8 billion in amputation-related medical expenses in the U.S. each year. The research team brings together interdisciplinary expertise in biomechanics, prosthetic design and clinical care, and students will be involved in all stages of this research. Outreach activities are planned to enhance understanding of the K12 population about working with individuals with disabilities, biomechanics, and prosthetics.The specific objectives of this proposal are (a) to characterize the effect of gastrocnemius-like ankle-knee coupling dynamics on human walking, then (b) to test the hypothesis that restoring this coupling for individuals with transtibial amputation will improve their gait symmetry and economy while also reducing unhealthy joint loading. Case study data, exoskeleton experiments, and walking simulations provide preliminary evidence that restoring this ankle-knee coupling may be beneficial to ILLA's; however, this has not yet been tested experimentally and it is currently unknown how individual ankle-knee coupling behaviors affect gait, or which are optimal. This study combines various measurement modalities to systematically evaluate biomechanics and mobility outcomes for ILLA walking with a range of ankle-knee coupling behaviors, followed by comparison between walking with vs. without an optimized artificial gastrocnemius. The artificial gastrocnemius will be controlled using a programmable, off-board prosthesis emulator. This study will generate new biomechanical data that provide insight into the functional benefits of ankle-knee coupling in bipedal walking and how these dynamics facilitate power transfer from the ankle. A feasibility study will be performed, with clinical partners, to assess if adding an artificial gastrocnemius will improve health- and mobility-related outcomes for ILLA's while they walk on passive and powered foot prostheses. This approach is innovative because it seeks to improve the function of all prosthetic feet by focusing on the transmission/interface with the body, rather than solely on the prosthetic foot itself. By enhancing walking performance, this research aims to improve mobility and physical activity outcomes for ILLA's.