Engineering and Technology
Shigeki Kubota, OTR, PhD
Professor
Ibaraki Prefectural University of Health Sciences
Ami-machi, Ibaraki, Japan
Hideki Kadone, PhD
Associate Professor
Center for Innovative Medicine and Engineering (CIME), University of Tsukuba
Tsukuba, Ibaraki, Japan
Yukiyo Shimizu, MD
Associate Professor
Department of Rehabilitation Medicine, University of Tsukuba
Tsukuba, Ibaraki, Japan
Yuichiro Soma, PhD
Asssitant Professor
Department of Rehabilitation Medicine, University of Tsukuba
Tsukuba, Ibaraki, Japan
Hirotaka Mutsuzaki, MD, PhD
Professor
Department of Orthopaedic Surgery, Ibaraki Prefectural University of Health Sciences
Ami-machi, Ibaraki, Japan
Masashi Yamazaki, MD
Professor
Department of Orthopaedic Surgery, Institute of Medicine, University of Tsukuba
Tsukuba, Ibaraki, Japan
Traumatic brachial plexus injury (BPI) causes severe upper limb dysfunction. Intercostal nerve to musculocutaneous nerve (ICN-MCN) transfer is a common surgical method for restoring elbow flexion, enabling 60–90% of patients to achieve active flexion (MMT grade ≥3). However, some patients show poor postoperative recovery. While factors like age and surgical timing affect outcomes, extended rehabilitation is also important. This study evaluated the electromyographic effectiveness of muscle re-education biofeedback training using the upper limb Hybrid Assistive Limb (HAL) following elbow flexor reconstruction.
Design:
Nine patients (mean age 35.5 years) with BPI from traffic accidents underwent ICN-MCN transfer. HAL-assisted elbow flexion training was performed once a week or month for a few months to 20 months, beginning a mean of 7.4 months post-surgery. All patients had biceps MMT grade 1 at training start. Outcomes included changes in MMT grade and biceps muscle activity, measured by surface EMG during training sessions. In five patients, EMG data were recorded during elbow flexion (MMT grades 1 and 2), both with and without HAL. Mean biceps amplitude was normalized using the maximal voluntary contraction (MVC) method. The Wilcoxon signed-rank test was used for statistical analysis.
Results:
Seven of nine patients improved to MMT grade 3 or higher post-training; three reached grade 4, four reached grade 3, and two remained at grade 2. The mean time to achieve MMT grade 3 was 15.9 ± 5.9 months postoperatively. In five EMG-evaluated patients, mean biceps amplitudes were significantly higher with HAL (75.1%) than without HAL (60.3%). Similar results were observed during conventional biofeedback.
Conclusion:
Biofeedback training using the upper limb HAL significantly enhances muscle activity and may support motor recovery after BPI. This approach appears to be an effective robotic-assisted rehabilitation method.
