Development of Adaptive Prosthetic Ankle-Foot Systems

描述（由申请人提供）： 许多退伍军人有下肢截肢由于创伤性损伤或并发症与糖尿病和血管疾病。在不平坦的地形上行走对于下肢截肢的人来说是不平衡和不舒适的，因为大多数当前的踝足假肢不能使其功能适应不同的倾斜表面。本项目将研究 一种仅使用被动机械部件就能在行走的每一步上适应不同地形的新型自适应踝足假肢的优点（即，而不需要马达或电池）。这种新系统还在行走的后期站立阶段提供跖屈，这应该会提高行走的效率。为了检查新的适应性踝足系统的潜在益处，将招募20名单侧经胫骨截肢的退伍军人进行研究。在首次访视期间，当退伍军人在跑步机上以五个表面坡度（-10、-5、0、+5和+10度）行走时，将测量假体踝关节扭矩与踝关节角度曲线。受试者还将走上并通过一系列坡道，以检查对表面斜坡的第一步适应。假体中的测力传感器与运动分析相结合，可以测量退伍军人在各种斜面上行走时的踝关节扭矩与踝关节角度。可以预期，当使用自适应踝足系统时，踝关节扭矩与踝关节角度的曲线将在上坡时向背屈方向移动，在下坡时向跖屈方向移动。踝关节扭矩与踝关节角度曲线的这些变化预计不会用于非适应性踝足系统（带EVO的Ossur VariFlex）的类似使用。在第二次和第三次访视中，相同的退伍军人将在测量其次最大摄氧量的同时，在一定范围的速度和表面坡度上使用适应性和非适应性踝足假体行走。对于每种情况（假体/速度或假体/坡度），受试者将在跑步机上行走6分钟，然后休息至少10分钟（或更长时间，如果需要恢复到基线摄氧量）。在第二次访视期间，受试者将以三种速度（0.75、1.00和1.25 m/s）使用自适应和非自适应踝足系统行走（随机顺序）。在第三次访视期间，受试者将以随机顺序在三个斜坡（-5、0和+5度）上使用两个踝足系统行走。与非自适应踝-足系统相比，自适应踝-足系统预期在速度和坡度方面均减少次最大氧摄取，因为其比当前被动非自适应踝-足系统存储和释放更多能量的能力以及其在每一步上使其功能适应表面坡度变化的能力。适应性踝足系统的耐久性测试将与研究实验同时进行。将使用国际标准化组织（ISO）22675测试方案对自适应踝足系统进行测试。在整个供资期间将进行设计修订，以提高适应性踝足系统的耐用性。开发活动的目标是通过ISO 22675 2，000，000次测试循环而无失效。为新的适应性踝足系统计划的研究和开发活动旨在提供证据，证明该系统能够在步行的每一步适应不同的表面坡度，并提高步行效率。这些活动将提供有关当前系统使用的设计方法的有用信息，同时提高退伍军人技术商业化的机会。

DESCRIPTION (provided by applicant): Many Veterans have lower-limb amputations due to traumatic injuries or complications associated with diabetes and vascular disease. Walking on uneven terrain is unbalanced and uncomfortable for persons with lower-limb amputations because most current ankle-foot prostheses do not adapt their function for different sloped surfaces. This project will examine the advantages of a new adaptable ankle-foot prosthesis that can adapt to different terrain on every step of walking using only passive mechanical parts (i.e., without the need for motors or batteries). This new system also provides plantarflexion in the late stance phase of walking, which should increase the efficiency of walking. To examine the potential benefits of the new adaptable ankle-foot system, twenty Veterans with unilateral transtibial amputations will be recruited for the study. During the first visit, the prosthetic ankle torque versus ankle angle curves will be measured while the Veterans walk on a treadmill at five surface slopes (-10, -5, 0, +5, and +10 degrees). Subjects will also walk up and over a series of ramps to examine first-step adaptation to surface slopes. A load cell in the prosthesis coupled with motion analysis will allow for the measurement of ankle torque vs. ankle angle as the Veterans walk on the various sloped surfaces. It is anticipated that the ankle torque versus ankle angle curves will shift towar dorsiflexion for uphill slopes and toward plantarflexion for downhill slopes when using the adaptable ankle-foot system. These shifts in the ankle torque vs. ankle angle curve are not expected for similar use of a non-adaptable ankle-foot system (Ossur VariFlex with EVO). In the second and third visits, the same Veterans will walk with both the adaptable and non-adaptable ankle- foot prostheses over a range of speeds and surface slopes while their submaximal oxygen uptake is measured. For each condition (prosthesis/speed or prosthesis/slope), subjects will walk for six minutes on a treadmill, followed by at least ten minutes of rest (or longer if needed to return to baseline oxygen uptake). During the second visit, subjects will walk at three speeds (0.75, 1.00, and 1.25 m/s) with both the adaptable and non-adaptable ankle-foot systems (in a random order). During the third visit, subjects will walk with both ankle-foot systems on three slopes (-5, 0, and +5 degrees) in a random order. The adaptable ankle-foot system is expected to reduce submaximal oxygen uptake compared with the non-adaptable ankle-foot system for both speeds and slopes due to its ability to store and release more energy than current passive non- adaptable ankle-foot systems and its ability to adapt its function on every step to changes in surface slope. Durability testing of the adaptable ankle-foot system will be conducted in parallel with research experiments. The adaptable ankle-foot system will be tested using the International Organization of Standards (ISO) 22675 testing protocol. Design revisions will occur throughout the funding period to improve the durability of the adaptable ankle-foot system. The goal of the development activities is to pass the ISO 22675 test of 2,000,000 cycles of testing without failure. The research and development activities planned for the new adaptable ankle-foot system are designed to provide evidence of the system's ability to adapt to different surface slopes on every step of walking as well as to increase walking efficiency. These activities will provide useful information regarding the design approach used by the current system, while improving the chances for commercialization of the technology for Veterans.