The Footropter: A Passive Prosthetic Prescription Tool With Adjustable Forefoot and Hindfoot Stiffness

Abstract

Commercially available prosthetic feet are fabricated to have a fixed forefoot and hindfoot stiffness that cannot be changed in a clinical setting. This does not allow for patients to quickly compare multiple prosthetic foot stiffnesses to choose the stiffness they like the most while walking. In this paper, we present the Footropter, a passive prosthetic foot prescription tool that allows Certified Prosthetists (CPs) to rapidly change both the forefoot and hindfoot stiffnesses. The forefoot stiffness is changed by repositioning a spring clamp along a length of unbonded fiberglass layers and the hindfoot stiffness is changed by repositioning a single heel spring support. We introduce the design and working principles, characterize the ranges of available forefoot and hindfoot stiffnesses, and demonstrate the utility of the Footropter through two preference and perception studies with two unilateral transtibial prosthesis users. The Footropter, when paired with a preference optimization algorithm, can enable CPs to integrate patients’ experiential input into the clinical prescription process.

Keywords

• Assistive technology
• prosthetic limbs
• variable-stiffness
• prosthesis design