Myoelectric performance of the reconstructed elbow flexor in patients with brachial plexus injuries

Traumatic adult brachial plexus injury is a debilitating injury. Myoelectric exoskeletons are functional tools for restoring elbow flexion. Electromyography signals are used for exoskeleton control, but a characterization specific to the traumatic adult brachial plexus injury population has yet to be performed. This study evaluated if adult patients with traumatic brachial plexus injury and a reconstructed elbow flexor can control a myoelectric exoskeleton. Adult patients who underwent surgical intervention to restore elbow flexion with traumatic brachial plexus injury were recruited for this cross-sectional study. The processed elbow flexor muscle signal and activation thresholds were used to evaluate criteria for exoskeleton control algorithm development. A single activation threshold can be utilized for exoskeleton control, but the calibration routine should consider the resting signal for both extended and flexed elbow positions. The data indicated a ‘settle-time’ following contraction is needed to prevent unintentional movement of the exoskeleton. All patients activated their elbow flexor above the activation threshold in the supported, flexed position. However, there were different abilities to generate multiple, discrete signals. These results were not specific to surgery, nerve implemented for reconstruction, or post-operative recovery time. Patients with a brachial plexus injury and a reconstructed elbow flexor demonstrated subject-specific capabilities for exoskeleton control.