Hybrid Assistive Limb in orthopaedic rehabilitation: cybernic treatment developed in Japan for neuromotor functional restoration.

PURPOSE: The Hybrid Assistive Limb (HAL) is a wearable cyborg system that uses surface bioelectrical signals to assist movement at the same time as the wearer's voluntary effort. This review explains its control principles and assesses the clinical evidence relevant to orthopaedic rehabilitation.

METHODS

Published clinical studies of HAL in orthopaedic rehabilitation were reviewed narratively and grouped by device configuration and clinical indication.

RESULTS

Across spinal cord injury and post-operative compressive myelopathy, training with the HAL lower-limb type was associated with improvements in walking speed, endurance, balance, trunk function and gait coordination. After total knee arthroplasty, the HAL single-joint and lower-limb types were associated with earlier gains in knee extension, less extension lag and pain, and better walking measures. In older adults, the HAL lumbar type supported repeated sit-to-stand and other hip-extension tasks, and improvements in mobility were reported. Upper-limb applications allowed assisted joint practice using weak residual muscle activity. Kinematic, electromyographic, motor-unit and cortical findings suggest that assistance linked to voluntary effort may influence sensorimotor activity during training.

CONCLUSION

HAL offers a distinctive approach to orthopaedic rehabilitation by turning residual bioelectrical activity into well-timed movement assistance and repeated sensory feedback. Available studies suggest that this approach can increase opportunities for voluntary, task-specific practice and may help to improve walking, joint movement and functional mobility in spinal and musculoskeletal conditions. These findings support the continued clinical development and evaluation of HAL as a rehabilitation option that responds to the user's intention.