# Assessing the effects of prosthetic foot stiffness and foot preference on stability, balance confidence, and satisfaction in transtibial prosthesis users: Protocol for a randomized, participant-masked crossover trial using a ‘test-drive’ strategy

## TL;DR

This study will test how different prosthetic foot stiffness levels affect walking stability and user preference in people with lower limb amputations.

## Contribution

The study introduces a 'test-drive' strategy to predict long-term outcomes of prosthetic foot use based on short-term trials.

## Key findings

- Prosthetic foot stiffness will be evaluated for its impact on stability across varied walking conditions.
- The 'test-drive' approach will be assessed for its ability to predict long-term balance confidence and foot preference.

## Abstract

With an appropriate prescription, the use of a lower limb prosthesis can help mitigate mobility limitations and increased risk of falling for people with lower limb amputation. Prosthetic feet cannot replicate all the functions of a biological foot-ankle. Different feet have different designs and properties, and therefore there are functional trade-offs. There is insufficient evidence as to the effects these different prosthetic foot properties have on users’ stability and balance, which would be helpful to guide clinical prosthesis prescription. Prosthesis users also rarely have opportunities to try walking with different prosthetic feet to give experiential input during the prescription process. Therefore, this study aims to determine 1) the effects of prosthetic foot stiffness on stability in lower limb prosthesis users while walking on varying terrains, and 2) whether a brief ‘test-drive’ strategy for selecting prosthetic feet can be used to predict longer term stability, balance confidence, and foot preference outcomes in lower limb prosthesis users.

In this multisite, participant-masked, randomized cross-over study, participants with unilateral, transtibial amputation will walk on different treadmill conditions (flat, incline, cross-slopes, uneven ground) with a variety of commercially-available prosthetic feet (‘actual’) and corresponding ‘emulated’ prosthetic feet in the laboratory. Participants will also wear the actual prosthetic feet at home and in the community for one week at a time. After each community trial, participants will return to the laboratory to complete walking trials on different terrains and at a range of speeds while we collect kinematic data. We will assess the effect of prosthetic foot stiffness on biomechanical and self-reported measures of stability. We will also assess how well brief ‘test-drive’ trials of walking with different prosthetic feet can predict longer-term self-reported measures of stability, balance confidence and preference.

This study was prospectively registered at www.clinicaltrials.gov (Clinical Trials Study ID: NCT05473065). Study start date: March 1, 2024.