Development of Adaptive Prosthetic Ankle-Foot Systems

描述(由申请人提供)： 许多退伍军人由于创伤或糖尿病和血管疾病相关的并发症而截肢。在不平坦的地形上行走对下肢截肢者来说是不平衡和不舒服的，因为目前大多数踝足假体不能适应不同的倾斜表面。本项目将研究 一种新型可适应的脚踝-脚假体的优点，它可以适应步行每一步的不同地形，只使用被动机械部件(即，不需要马达或电池)。这个新的系统还在行走的后期站立阶段提供了足屈功能，这应该会提高行走的效率。为了检验新的适应性踝足系统的潜在益处，20名单侧胫骨截肢的退伍军人将被招募参加这项研究。在第一次访问中，当退伍军人在跑步机上以五种表面坡度(-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的曲线。受试者还将走上一系列坡道，检查第一步对地面斜坡的适应情况。当退伍军人在不同的倾斜表面行走时，假体中的称重传感器结合运动分析将允许测量脚踝扭矩与脚踝角度的关系。当使用自适应的踝足系统时，预计踝关节扭矩与踝关节角度的关系曲线将在上坡时向背屈方向移动，在下坡时向足底屈曲方向移动。对于非适应性踝足系统(Ossur VariFlex With EVO)，踝关节扭矩与踝关节角度曲线的这些变化不适用于类似的用途。在第二次和第三次访问中，相同的退伍军人将使用适应性和非适应性踝足假体在一定的速度和表面坡度范围内行走，同时测量他们的亚最大摄氧量。对于每种情况(假体/速度或假体/坡度)，受试者将在跑步机上步行6分钟，然后至少休息10分钟(如果需要恢复到基线摄氧量，则休息更长时间)。在第二次访问中，受试者将以三种速度(0.75米/S、1.00米/S和1.25m/S)步行，并使用适应性和非适应性踝足系统(按随机顺序)。在第三次访问中，受试者将以随机顺序在三个坡度(-5度、0度和5度)上用两个脚踝-脚系统行走。与非适应性踝足系统相比，适应性踝足系统在速度和坡度上都有望减少亚最大摄氧量，因为它比目前被动的非适应性踝足系统能够储存和释放更多的能量，并且它能够根据体表坡度的变化调整每一步的功能。适应性踝足系统的耐久性测试将与研究实验并行进行。这种可适应的脚踝-足部系统将使用国际标准化组织22675测试协议进行测试。在整个筹资期间，将进行设计修订，以提高适应性脚踝-足部系统的耐用性。开发活动的目标是无故障地通过2000,000,000个测试周期的ISO 22675测试。为新的适应性脚踝-足部系统计划的研究和开发活动旨在提供证据，证明该系统有能力适应步行每一步的不同表面坡度，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，同时增加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.