Stance controlled knee flexion improves stimulation driven walking after spinal cord injury

Area of Science:

• Biomedical Engineering
• Neuroprosthetics
• Rehabilitation Robotics

Background:

• Functional neuromuscular stimulation (FNS) aids walking post-spinal cord injury by activating muscles.
• Hybrid neuroprostheses (HNPs) combine FNS with orthotics for enhanced walking.
• Advanced HNPs aim to improve joint coordination during swing and stability during stance.

Purpose of the Study:

• Investigate the impact of controlled knee flexion during stance on gait restoration.
• Compare FNS-only walking with a VIKM-HNP system allowing controlled knee motion.

Main Methods:

• A single participant with T7 spinal cord injury was studied.
• Two walking techniques were compared: FNS-only (stiff knee) and VIKM-HNP (controlled knee motion).
• A variable impedance knee mechanism (VIKM) controlled knee flexion during stance phases.

Main Results:

• VIKM-HNP resulted in more natural stance phase knee angles and reduced hyperextension.
• Knee flexion in VIKM-HNP reduced impact forces and increased gait speed during loading response.
• Improved pre-swing knee flexion aided swing phase, especially with compromised stimulation response.

Conclusions:

• Controlled knee flexion in HNPs offers significant advantages for walking restoration.
• This technology could enable challenging non-level walking tasks like navigating slopes and stairs.
• VIKM-HNP demonstrates potential for more natural and functional gait recovery.