IEEE Trans Neural Syst Rehabil Eng. 2018 Apr;26(4):894-903. doi: 10.1109/TNSRE.2018.2811544.
Discrete, rapid (i.e., ballistic like) muscle activation patterns have been observed in ankle muscles (i.e., plantar flexors and dorsiflexors) of able-bodied individuals during voluntary posture control. This observation motivated us to investigate whether transtibial amputees are capable of generating such a ballistic-like activation pattern accurately using their residual ankle muscles in order to assess whether the volitional postural control of a powered ankle prosthesis using proportional myoelectric control via residual muscles could be feasible. In this paper, we asked ten transtibial amputees to generate ballistic-like activation patterns using their residual lateral gastrocnemius and residual tibialis anterior to control a computer cursor via proportional myoelectric control to hit targets positioned at 20% and 40% of maximum voluntary contraction of the corresponding residual muscle. During practice conditions, we asked amputees to hit a single target repeatedly. During testing conditions, we asked amputees to hit a random sequence of targets. We compared movement time to target and end-point accuracy. We also examined motor recruitment synchronization via time-frequency representations of residual muscle activation. The result showed that median end-point error ranged from -0.6% to 1% maximum voluntary contraction across subjects during practice, which was significantly lower compared to testing ( ). Average movement time for all amputees was 242 ms during practice and 272 ms during testing. Motor recruitment synchronization varied across subjects, and amputees with the highest synchronization achieved the fastest movement times. End-point accuracy was independent of movement time. Results suggest that it is feasible for transtibial amputees to generate ballistic control signals using their residual muscles. Future work on volitional control of powered power ankle prostheses might consider anticipatory postural control based on ballistic-like residual muscle activation patterns and direct continuous proportional myoelectric control.
在自主姿势控制过程中，观察到健全个体的踝关节肌肉（即跖屈肌和背屈肌）中存在离散的、快速（即弹道样）的肌肉激活模式。这一观察结果促使我们研究是否截瘫患者能够利用其残余踝关节肌肉准确地产生这种弹道样激活模式，以评估是否可以通过残肢肌肉的比例肌电控制来实现动力踝关节假肢的自主姿势控制。在本文中，我们要求 10 名截瘫患者利用其残余的外侧腓肠肌和胫骨前肌产生弹道样的激活模式，通过比例肌电控制来控制计算机光标，以击中 20%和 40%最大残余肌肉收缩力的目标。在练习条件下，我们要求患者反复击中单个目标。在测试条件下，我们要求患者随机击中一系列目标。我们比较了到达目标的运动时间和终点精度。我们还通过残余肌肉激活的时频表示检查了运动募集同步性。结果表明，在练习过程中，中位数终点误差范围在 -0.6%至 1%最大自愿收缩之间，与测试相比显著降低（）。所有患者的平均运动时间在练习时为 242ms，测试时为 272ms。运动募集同步性因人而异，同步性最高的患者达到最快的运动时间。终点精度与运动时间无关。结果表明，截瘫患者利用其残余肌肉产生弹道控制信号是可行的。未来对动力踝关节假肢的自主控制研究可能会考虑基于弹道样残余肌肉激活模式的预测性姿势控制和直接连续比例肌电控制。
