Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Center for Extreme Bionics, MIT Media Lab, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Sci Robot. 2017 May 31;2(6). doi: 10.1126/scirobotics.aan2971.
Prosthetic limb control is fundamentally constrained by the current amputation procedure. Since the U.S. Civil War, the external prosthesis has benefited from a pronounced level of innovation, but amputation technique has not significantly changed. During a standard amputation, nerves are transected without the reintroduction of proper neural targets, causing painful neuromas and rendering efferent recordings infeasible. Furthermore, the physiological agonist-antagonist muscle relationships are severed, precluding the generation of musculotendinous proprioception, an afferent feedback modality critical for joint stability, trajectory planning, and fine motor control. We establish an agonist-antagonist myoneural interface (AMI), a unique surgical paradigm for amputation. Regenerated free muscle grafts innervated with transected nerves are linked in agonist-antagonist relationships, emulating the dynamic interactions found within an intact limb. Using biomechanical, electrophysiological, and histological evaluations, we demonstrate a viable architecture for bidirectional signaling with transected motor nerves. Upon neural activation, the agonist muscle contracts, generating electromyographic signal. This contraction in the agonist creates a stretch in the mechanically linked antagonist muscle, producing afferent feedback, which is transmitted through its motor nerve. Histological results demonstrate regeneration and the presence of the spindle fibers responsible for afferent signal generation. These results suggest that the AMI will not only produce robust signals for the efferent control of an external prosthesis but also provide an amputee's central nervous system with critical musculotendinous proprioception, offering the potential for an enhanced prosthetic controllability and sensation.
假肢控制从根本上受到当前截肢手术的限制。自美国内战以来，外部假肢受益于明显的创新水平，但截肢技术并没有显著改变。在标准截肢中，神经被切断，而没有重新引入适当的神经靶标，导致疼痛性神经瘤，并使传出记录变得不可行。此外，生理上的拮抗肌关系被切断，从而无法产生肌肌腱本体感觉，这是一种对关节稳定性、轨迹规划和精细运动控制至关重要的传入反馈模式。我们建立了一个拮抗肌神经接口（AMI），这是一种独特的截肢手术范例。用切断的神经支配的再生游离肌肉移植物以拮抗关系连接，模拟了完整肢体中发现的动态相互作用。通过生物力学、电生理学和组织学评估，我们展示了与切断的运动神经进行双向信号传递的可行架构。在神经激活时，拮抗肌收缩，产生肌电图信号。这种在拮抗剂中的收缩在机械连接的拮抗剂肌肉中产生拉伸，产生传入反馈，通过其运动神经传递。组织学结果表明存在再生和负责传入信号产生的梭形纤维。这些结果表明，AMI 不仅将产生用于外部假肢的传出控制的强大信号，而且还将为截肢者的中枢神经系统提供关键的肌肌腱本体感觉，从而提供增强的假肢可控性和感觉的潜力。
