Safety and efficacy of robotic elbow training using the upper limb single-joint hybrid assistive limb combined with conventional rehabilitation for bilateral obstetric brachial plexus injury with co-contraction: a case report

[Purpose] Obstetric brachial plexus injuries are accompanied by co-contractions due to misdirection of regenerated nerve fibers. The result is inhibition of arm movement necessary for activities of daily living. Rehabilitation is important to prevent joint contracture and muscle atrophy in such cases. A single-joint hybrid assistive limb is a new wearable robot that can assist in elbow joint motion by detecting muscle action potentials on the upper limb surface. Inhibiting co-contractions due to obstetric brachial plexus injuries with this device may help with performance of activities of daily living. This study aimed to evaluate the safety and efficacy of using a single-joint hybrid assistive limb combined with conventional rehabilitation in a patient with obstetric brachial plexus injuries. [Participant and Methods] A 40-year-old male with bilateral obstetric brachial plexus injuries and co-contractions of the biceps and deltoid underwent rehabilitation training using the single-joint hybrid assistive limb 3 times a week for 12 sessions (4 weeks) in both upper limbs. [Results] The patient completed all 12 sessions of training using the single-joint hybrid assistive limb with no adverse events. Improvements in flexion strength in the left elbow, active flexion range of motion in both elbows, and functional tests in the right arm were observed. [Conclusion] Elbow training using the newly developed single-joint hybrid assistive limb combined with conventional rehabilitation can be performed without severe adverse events and may improve muscle strength, range of motion, and arm functions in adults with obstetric brachial plexus injuries and bilateral co-contractions of the deltoid and biceps muscles.