Proximal powered knee placement: a case study

2026-02-19

AI Summary

This study addresses the degradation of gait biomechanics and increased metabolic cost in powered prosthetic knees caused by added distal mass. To mitigate these issues, the work proposes relocating the actuation system proximally—above the knee—thereby optimizing mass distribution rather than merely minimizing weight. A custom prototype was developed and evaluated through kinematic analysis and multi-terrain gait experiments, including level ground, ramps, and stairs, demonstrating enhanced control robustness and functional feasibility. Experimental results from a single subject showed a 9.2% increase in walking speed and a 3.6% rise in cadence, while knee range of motion and peak angular velocity remained stable. These findings confirm that the proposed configuration effectively balances assistive performance with reduced user burden.

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Abstract

Lower limb amputation affects millions worldwide, leading to impaired mobility, reduced walking speed, and limited participation in daily and social activities. Powered prosthetic knees can partially restore mobility by actively assisting knee joint torque, improving gait symmetry, sit-to-stand transitions, and walking speed. However, added mass from powered components may diminish these benefits, negatively affecting gait mechanics and increasing metabolic cost. Consequently, optimizing mass distribution, rather than simply minimizing total mass, may provide a more effective and practical solution. In this exploratory study, we evaluated the feasibility of above-knee powertrain placement for a powered prosthetic knee in a small cohort. Compared to below-knee placement, the above-knee configuration demonstrated improved walking speed (+9.2% for one participant) and cadence (+3.6%), with mixed effects on gait symmetry. Kinematic measures indicated similar knee range of motion and peak velocity across configurations. Additional testing on ramps and stairs confirmed the robustness of the control strategy across multiple locomotion tasks. These preliminary findings suggest that above-knee placement is functionally feasible and that careful mass distribution can preserve the benefits of powered assistance while mitigating adverse effects of added weight. Further studies are needed to confirm these trends and guide design and clinical recommendations.

Problem

• powered prosthetic knee
• mass distribution
• gait mechanics
• mobility restoration
• above-knee amputation

Innovation

• proximal placement
• powered prosthetic knee
• mass distribution
• gait performance
• above-knee powertrain