Design and Development of a Powered Myoelectric Elbow Orthosis for Neuromuscular Injuries.

INTRODUCTION: Recovering from neuromuscular injuries or conditions can be a challenging journey that involves complex surgeries and extensive physical rehabilitation. During this process, individuals often rely on orthotic devices to support and enable movement of the affected limb. However, users have criticized current commercially available powered orthotic devices for their bulky and heavy design. To address these limitations, we developed a novel powered myoelectric elbow orthosis. MATERIALS AND METHODS: The orthosis incorporates 3 mechanisms: a solenoid brake, a Bowden cable-powered constant torque elbow mechanism, and an extension limiter. The device controller and battery are in a backpack to reduce the weight on the affected arm. We performed extensive calculations and testing to ensure that the orthosis could withstand at least 15 Nm of elbow torque. We developed a custom software effectively control the orthosis, enhancing its usability and functionality. A certified orthotist fitted a subject who had undergone a gracilis free functioning muscle transfer surgery with the device. We studied the subject under Mayo clinic IRB no. 20-006849 and obtained objective measurements to assess the orthosis's impact on upper extremity functionality during daily activities. RESULTS: The results are promising since the orthosis significantly improved elbow flexion range of motion by 40° and reduced compensatory movements at the shoulder (humerothoracic joint) by 50°. Additionally, the subject was able to perform tasks which were not possible before, such as carrying a basket with weights, highlighting the enhanced functionality provided by the orthosis. CONCLUSION: In brief, by addressing the limitations of existing devices, this novel powered myoelectric elbow orthosis offers individuals with neuromuscular injuries/conditions improved quality of life. Further research will expand the patient population and control mechanisms.

Upper extremity asymmetry due to nerve injuries or central neurologic conditions: a scoping review.

BACKGROUND: Peripheral nerve injuries and central neurologic conditions can result in extensive disabilities. In cases with unilateral impairment, assessing the asymmetry between the upper extremity has been used to assess outcomes of treatment and severity of injury. A wide variety of validated and novel tests and sensors have been utilized to determine the upper extremity asymmetry. The purpose of this article is to review the literature and define the current state of the art for describing upper extremity asymmetry in patients with peripheral nerve injuries or central neurologic conditions. METHOD: An electronic literature search of PubMed, Scopus, Web of Science, OVID was performed for publications between 2000 to 2022. Eligibility criteria were subjects with neurological conditions/injuries who were analyzed for dissimilarities in use between the upper extremities. Data related to study population, target condition/injury, types of tests performed, sensors used, real-world data collection, outcome measures of interest, and results of the study were extracted. Sackett's Level of Evidence was used to judge the quality of the articles. RESULTS: Of the 7281 unique articles, 112 articles met the inclusion criteria for the review. Eight target conditions/injuries were identified (Brachial Plexus Injury, Cerebral Palsy, Multiple Sclerosis, Parkinson's Disease, Peripheral Nerve Injury, Spinal Cord Injury, Schizophrenia, and stroke). The tests performed were classified into thirteen categories based on the nature of the test and data collected. The general results related to upper extremity asymmetry were listed for all the reviewed articles. Stroke was the most studied condition, followed by cerebral palsy, with kinematics and strength measurement tests being the most frequently used tests. Studies with a level of evidence level II and III increased between 2000 and 2021. The use of real-world evidence-based data, and objective data collection tests also increased in the same period. CONCLUSION: Adequately powered randomized controlled trials should be used to study upper extremity asymmetry. Neurological conditions other than stroke should be studied further. Upper extremity asymmetry should be measured using objective outcome measures like motion tracking and activity monitoring in the patient's daily living environment.

Characterization of elbow flexion torque after nerve reconstruction of patients with traumatic brachial plexus injury.

BACKGROUND: The modified British Medical Research Council muscle grading system remains the primary method for assessing outcomes following surgical intervention despite its subjectivity and numerous inherent flaws. A new objective outcome measure of elbow function in patients with a brachial plexus injury is proposed. METHODS: 11 patients with a reconstructed brachial plexus (nerve reconstruction) and 10 unimpaired control subjects were evaluated. A custom apparatus measuring elbow flexion torque was developed. The subjects were asked to match their elbow flexion torque to a predefined torque. Time taken to achieve this predefined elbow flexion torque (latency) and duration of steady torque output were used as outcome measures. RESULTS: Healthy individuals were better at maintaining and regulating elbow torque. The patients with a brachial plexus injury showed similar latency while increasing their elbow torque (normalized to maximum elbow torque) but lacked the ability to modulate the latency with demand as the healthy subjects. INTERPRETATION: This novel measure provides objective information regarding the patient's ability to control elbow torque after nerve reconstruction.

Muscle activation for targeted elbow force production following surgical reconstruction in adults with brachial plexus injury.

Nerve transfer or grafting surgery to restore elbow flexion in peripheral nerve injuries has been an effective technique, but alters neuromuscular control compared with healthy individuals. This study compared neuromuscular control in the elbow flexors of 11 unimpaired control subjects and 11 adult patients with traumatic brachial plexus injury who underwent a nerve transfer or grafting procedure to the biceps motor branch to restore elbow flexion. The subjects performed a series of trials to generate a specific percentage of their maximum elbow torque. Each trial had an increasing and decreasing stairstep torque pattern that the subjects were asked to match. The amount of time that the subject's elbow torque was maintained within 5% of the target torque was calculated. The hypothesis was that there was a significant difference in the neuromuscular control between the two groups during elbow isometric torque generation. A secondary hypothesis was that a relationship existed between the neuromuscular control and the torque level for each group. The results demonstrated that neuromuscular control was different between the groups and there were significant differences in how torque levels are generated. The control group more easily modulated their myoelectric activation and achieved greater neuromuscular control variability with varying torque demand. The nerve transfer or grafting group could not modulate their myoelectric activation with changing torque demands. Further studies focusing on the improvement of neuromuscular control are needed to optimize functional outcomes in nerve injury patients.