Automatic vs hand-controlled walking of paraplegics.

Area of Science:

• Biomedical Engineering
• Rehabilitation Technology
• Neuroscience

Background:

• Paraplegia results in impaired walking ability due to spinal cord injury.
• Functional Electrical Stimulation (FES) offers a potential method for restoring assisted walking.
• Developing effective control strategies for FES-assisted walking is crucial for improving patient mobility and quality of life.

Purpose of the Study:

• To design and evaluate a rule-based control system for FES-assisted walking in individuals with paraplegia.
• To compare the performance of automatic FES control modes with hand-controlled walking.
• To assess user experience and physiological outcomes across different walking conditions.

Main Methods:

• A customized 3D model of paraplegic walking was used to determine muscle activation patterns.
• An artificial neural network (radial-basis function) learned the correlation between muscle activation and walking kinematics.
• An FES system activated eight muscle groups, controlling hip, knee, and ankle joints, with evaluations in six spinal cord-injured subjects.

Main Results:

• Automatic FES control significantly increased walking speed (nearly threefold) and reduced energy consumption compared to hand control.
• While objective measures favored faster, more energy-efficient modes (near-ballistic), subjective feedback indicated a preference for slower walking speeds.
• Despite improvements, energy expenditure remained higher than in able-bodied individuals.

Conclusions:

• Rule-based automatic control enhances FES-assisted walking efficiency and speed in paraplegic individuals.
• User preference for slower walking suggests challenges in synchronizing voluntary trunk/arm movements with automated leg control.
• Further research is needed to optimize control strategies and address user comfort and integration challenges.