Walking for short distances and turning in lower-limb amputees: a study in low-cost prosthesis users

TL;DR

This study investigates how lower-limb amputees with passive prostheses walk in short distances and turns, revealing increased energy costs and suggesting improvements for prosthesis design and rehabilitation.

Contribution

It introduces an analysis of walking behaviors involving turns and short distances in amputees, highlighting differences from non-amputees and proposing a new performance measure.

Findings

Preferred walking speeds are lower for short distances and small radii turns.

Estimated energy costs for speed changes and turning are higher in amputees.

Measuring speeds across distances and radii offers a robust performance metric.

Abstract

Preferred walking speed is a widely-used performance measure for people with mobility issues, but is usually measured in straight line walking for fixed distances or durations. However, daily walking involves walking for bouts of different distances and walking with turning. Here, we studied walking for short distances and walking in circles in unilateral lower-limb amputees wearing an above or below-knee passive prosthesis, specifically, a Jaipur foot prosthesis. Analogous to earlier results in non-amputees, we found that their preferred walking speeds are lower for short distances and lower for circles of smaller radii. Using inverse optimization, we estimated the cost of changing speeds and turning such that the observed preferred walking speeds in our experiments minimizes the total energy cost. The inferred costs of changing speeds and turning were much larger than for non-amputees. These findings could inform prosthesis design and rehabilitation therapy to better assist changing speeds and turning tasks in amputee walking. Further, measuring the preferred speed for a range of distances and radii is a more robust subject-specific measure of walking performance.