Recycling energy to restore impaired ankle function during human walking

Area of Science:

• Biomechanics
• Robotics
• Human locomotion

Background:

• Walking involves significant energy dissipation, particularly at step transitions.
• Ankle function is crucial for energy restoration during push-off; impairment often leads to reduced walking economy.
• Assistive devices could potentially capture and reuse dissipated energy, negating the need for muscular energy replacement.

Purpose of the Study:

• To develop and evaluate a microprocessor-controlled artificial foot capable of energy recycling.
• To investigate the impact of energy recycling on ankle push-off work and metabolic energy expenditure in individuals with artificially impaired ankles.

Main Methods:

• Development of a microprocessor-controlled artificial foot designed to capture and reuse dissipated leg energy.
• Testing the artificial foot on subjects with artificially impaired ankles during walking.
• Comparison of walking economy with the energy-recycling prosthesis versus a conventional prosthesis and normal walking.

Main Results:

• A conventional prosthesis, compared to normal walking, reduced ankle push-off work and increased net metabolic energy expenditure by 23%.
• The energy-recycling artificial foot restored normal ankle push-off.
• The energy-recycling prosthesis reduced the net metabolic energy penalty to 14% compared to normal walking.

Conclusions:

• Reduced ankle push-off is a significant contributor to increased metabolic energy expenditure in individuals with ankle impairments.
• Energy recycling via an assistive device is a viable strategy to reduce the metabolic cost of walking with ankle impairments.