Background. Robotic exoskeleton devices have become a promising modality for restoration of extremity function in individuals with limb loss or functional weakness. However, there exists no consistent or reliable way to record efferent motor action potentials from intact peripheral nerves to control device movement. Peripheral nerve motor action potentials are similar in amplitude to that of background noise, producing an unfavorable signal-to-noise ratio (SNR) that makes these signals difficult to detect and interpret. To address this issue, we have developed the muscle cuff regenerative peripheral nerve interface (MC-RPNI), a construct consisting of a free skeletal muscle graft wrapped circumferentially around an intact peripheral nerve. Over time, the muscle graft regenerates, and the intact nerve undergoes collateral axonal sprouting to reinnervate the muscle. The MC-RPNI amplifies efferent motor action potentials by several magnitudes, thereby increasing the SNR, allowing for higher fidelity signaling and detection of motor intention. The goal of this study was to characterize the signaling capabilities and viability of the MC-RPNI over time. Methods. Thirty-seven rats were randomly assigned to one of five experimental groups (Groups A–E). For MC-RPNI animals, their contralateral extensor digitorum longus (EDL) muscle was harvested and trimmed to either 8 mm (Group A) or 13 mm (Group B) in length, wrapped circumferentially around the intact ipsilateral common peroneal (CP) nerve, secured, and allowed to heal for 3 months. Additionally, one 8 mm (Group C) and one 13 mm (Group D) length group had an epineurial window created in the CP nerve immediately preceding MC-RPNI creation. Group E consisted of sham surgery animals. At 3 months, electrophysiologic analyses were conducted to determine the signaling capabilities of the MC-RPNI. Additionally, electromyography and isometric force analyses were performed on the CP-innervated EDL to determine the effects of the MC-RPNI on end organ function. Following evaluation, the CP nerve, MC-RPNI, and ipsilateral EDL muscle were harvested for histomorphometric analysis. Results. Study endpoint analysis was performed at 3 months post-surgery. All rats displayed visible muscle contractions in both the MC-RPNI and EDL following proximal CP nerve stimulation. Compound muscle action potentials were recorded from the MC-RPNI following proximal CP nerve stimulation and ranged from 3.67 0.58 mV to 6.04 1.01 mV, providing efferent motor action potential amplification of 10–20 times that of a normal physiologic nerve action potential. Maximum tetanic isometric force (F _o) testing of the distally-innervated EDL muscle in MC-RPNI groups produced F _o (2341 114 mN–2832 102 mN) similar to controls (2497 122 mN), thus demonstrating that creation of MC-RPNIs did not adversely impact the function of the distally-innervated EDL muscle. Overall, comparison between all MC-RPNI sub-groups did not reveal any statistically significant differences in signaling capabilities or negative effects on distal-innervated muscle function as compared to the control group. Conclusions. MC-RPNIs have the capability to provide efferent motor action potential amplification from intact nerves without adversely impacting distal muscle function. Neither the size of the muscle graft nor the presence of an epineurial window in the nerve had any significant impact on the ability of the MC-RPNI to amplify efferent motor action potentials from intact nerves. These results support the potential for the MC-RPNI to serve as a biologic nerve interface to control advanced exoskeleton devices.

背景. 机器人外骨骼设备已成为恢复肢体缺失或功能虚弱个体肢体功能的一种有前途的方式。然而，没有一致或可靠的方法来记录来自完整外周神经的传出运动动作电位以控制设备运动。周围神经运动动作电位的幅度与背景噪声的幅度相似，产生不利的信噪比 (SNR)，使这些信号难以检测和解释。为了解决这个问题，我们开发了肌肉袖带再生周围神经接口 (MC-RPNI)，这是一种由环绕完整周围神经的游离骨骼肌移植物组成的结构。随着时间的推移，肌肉移植物会再生，并且完整的神经经历侧支轴突发芽以重新支配肌肉。MC-RPNI 将传出运动动作电位放大几个数量级，从而增加 SNR，允许更高保真度的信号传递和运动意图检测。本研究的目标是表征 MC-RPNI 随着时间的推移的信号能力和可行性。方法. 三十七只大鼠被随机分配到五个实验组（A-E 组）之一。对于 MC-RPNI 动物，收获它们的对侧趾长伸肌 (EDL) 并将其修剪为 8 毫米（A 组）或 13 毫米（B 组），环绕完整的同侧腓总（CP）神经，固定，并允许愈合3个月。此外，一个 8 毫米（C 组）和一个 13 毫米（D 组）长度的组在 MC-RPNI 创建之前立即在 CP 神经中创建了一个神经外膜窗。E组由假手术动物组成。在 3 个月时，进行电生理分析以确定 MC-RPNI 的信号传递能力。此外，还对 CP 支配的 EDL 进行了肌电图和等长力分析，以确定 MC-RPNI 对终末器官功能的影响。结果。研究终点分析在术后 3 个月进行。在近端 CP 神经刺激后，所有大鼠在 MC-RPNI 和 EDL 中都显示出可见的肌肉收缩。在近端 CP 神经刺激后，从 MC-RPNI 记录复合肌肉动作电位，范围从 3.67±0.58 mV 到 6.04±1.01 mV，提供正常生理神经动作电位的 10-20 倍的传出运动动作电位放大。MC-RPNI 组中远端神经支配的 EDL 肌肉的最大强直等长力 ( F _o ) 测试产生F _o(2341 114 mN–2832 102 mN) 类似于对照 (2497 122 mN)，从而证明 MC-RPNI 的产生不会对远端神经支配的 EDL 肌肉的功能产生不利影响。总体而言，与对照组相比，所有 MC-RPNI 亚组之间的比较并未显示信号能力或对远端神经支配肌肉功能的负面影响有任何统计学上的显着差异。结论. MC-RPNI 能够从完整的神经提供传出运动动作电位放大，而不会对远端肌肉功能产生不利影响。肌肉移植物的大小和神经中是否存在神经外窗对 MC-RPNI 放大来自完整神经的传出运动动作电位的能力没有任何显着影响。这些结果支持 MC-RPNI 作为生物神经接口来控制先进外骨骼设备的潜力。