Fleming Aaron, Huang Stephanie, Huang He Helen
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:2128-2131. doi: 10.1109/EMBC.2018.8512674.
Recently there has been considerable interest in the use of electromyography (EMG) for the control of powered, lower-limb prostheses. However, little is understood regarding amputee residual muscle, specifically the ability for lower-limb amputees to coordinate previously antagonist residual muscles for different control tasks. In this study, we aimed to investigate the capability of transtibial amputees in coordinating residual gastrocnemius and tibialis anterior for performing a high-level task. Specifically, we examined how three transtibial amputees and one ablebodied subject used residual and intact ankle muscles to balance a virtual inverted pendulum. Subjects controlled the pendulum by modulating stiffness of the base joint proportional to the level of EMG signal exerted. We conducted ten trials for each subject and quantified success of task performance by area of overall sway and number of falls (termed failure). Amputees successfully reduced number of failures, though not to the extent of able-bodied subjects. Interestingly, while able-bodied subjects reduced overall pendulum sway, amputees did not. EMG coordination patterns that preceded failure for amputees were different than that of able-bodied subjects. These results suggest that amputees have altered ability to coordinate muscle post-amputation; however, all subjects can improve the task performance and learn to reduce EMG coordination patterns that led to task failure. Further study is required to investigate the limit of amputees in learning of coordination between antagonist residual muscles in order to inform future neural control of prosthetic legs.
最近，人们对使用肌电图（EMG）来控制动力型下肢假肢产生了浓厚兴趣。然而，对于截肢者的残余肌肉，特别是下肢截肢者协调先前拮抗的残余肌肉以完成不同控制任务的能力，人们了解甚少。在本研究中，我们旨在调查经胫截肢者协调残余腓肠肌和胫前肌以执行高级任务的能力。具体而言，我们研究了三名经胫截肢者和一名健全受试者如何利用残余和完整的踝关节肌肉来平衡一个虚拟倒立摆。受试者通过根据所施加的EMG信号水平调节基础关节的刚度来控制摆。我们为每个受试者进行了十次试验，并通过总体摆动面积和跌倒次数（称为失败）来量化任务执行的成功率。截肢者成功减少了失败次数，尽管程度不及健全受试者。有趣的是，健全受试者减少了摆的总体摆动，而截肢者则没有。截肢者失败前的EMG协调模式与健全受试者不同。这些结果表明，截肢者截肢后协调肌肉的能力发生了改变；然而，所有受试者都可以提高任务表现，并学会减少导致任务失败的EMG协调模式。需要进一步研究来调查截肢者在学习拮抗残余肌肉之间协调方面的极限，以便为未来假肢腿的神经控制提供信息。
