Fast walking with swing extension assistance in a nominally passive semi-powered prosthetic knee

Area of Science:

• Biomechanics
• Prosthetics Engineering
• Gait Analysis

Background:

• Microprocessor-controlled knee prostheses (MPKs) are typically passive during the swing phase.
• Healthy individuals use powered knee extension during fast walking for increased speed.

Purpose of the Study:

• To investigate the impact of powered swing extension assistance in passive MPKs at fast walking speeds.
• To evaluate user experience and gait adaptations with powered knee prostheses.

Main Methods:

• Three participants with transfemoral amputation walked on a treadmill at various speeds.
• Comparison of gait parameters with and without powered swing extension assistance.

Main Results:

• Powered swing extension significantly increased knee angular velocity during swing.
• Increased swing extension led to a longer latency period before heel strike, not reduced swing time.
• Participants reported positive feedback on assistance but disliked terminal impact, especially at lower speeds.

Conclusions:

• Powered swing extension assistance in MPKs can increase swing extension velocity.
• Users adapt by increasing latency, prioritizing knee extension assurance over reduced swing time.
• Terminal impact is a significant drawback requiring further optimization for user comfort and safety.