Effect of robot-assisted gait training on the biomechanical properties of burn scars: a single-blind, randomized controlled trial

BACKGROUND: Robot-assisted gait training (RAGT) is more effective in the range of motion (ROM) and isometric strength in patients with burns than conventional training. However, concerns have been raised about whether RAGT might negatively affect the scars of patients with burns. Therefore, we investigated the effects of RAGT-induced mechanical load on the biomechanical properties of burn scars. METHODS: This was a single-blind, randomized clinical trial conducted on inpatients admitted to the Department of Rehabilitation Medicine between September 2020 and August 2021. RAGT was conducted for 30 min per day, five days a week for 12 weeks and the control group received conventional gait training for 12 weeks. The pre-training ROM of lower extremity joints was evaluated and the levels of melanin, erythema, trans-epidermal water loss, scar distensibility and elasticity were assessed before training and at 4 and 12 weeks after training. Finally, 19 patients in the gait assistance robot (GAR) group and 20 patients in the control group completed the 12-week trial and all evaluations. RESULTS: There were no significant differences in the epidemiologic characteristics, pre-training ROM of joints and pre-training biomechanical properties of the burn scar between the groups (p > 0.05 for all). None of the patients experienced skin abrasion around the burn scar where the fastening belts were applied or musculoskeletal or cardiovascular adverse events during the training. Scar thickness significantly increased in both groups (p = 0.037 and p = 0.019) and scar distensibility significantly decreased in the control group (p = 0.011) during the training. Hysteresis was significantly decreased in the GAR group during the training (p = 0.038). The GAR and control groups showed significant difference in the change in the values of hysteresis between pre-training and 12 weeks after training (p = 0.441 and p = 0.049). CONCLUSIONS: RAGT significantly decreased hysteresis in hypertrophic burn scars and did not cause a significant decrease in skin distensibility. Moreover, no skin complications around the burn scars were detected during RAGT. TRIAL REGISTRATION: This study registered on the Clinical Research Information Service (KCT0005204).