# The Overlay, a New Solution for Volume Variations in the Residual Limb for Individuals with a Transtibial Amputation

## TL;DR

A new device called the Overlay helps manage volume changes in the residual limb of amputees, offering better comfort and less pain than traditional methods.

## Contribution

The Overlay is introduced as a novel pneumatic solution for managing residual limb volume variations in transtibial amputees.

## Key findings

- The Overlay improved comfort and reduced pain compared to prosthetic folds during functional tasks.
- Less hip flexion was observed with the Overlay during sit-to-stand movements.
- Participants showed better satisfaction with the Overlay after two weeks of use.

## Abstract

Background: The company Ethnocare has developed the Overlay, a new pneumatic solution for managing volumetric variations (VVs) of the residual limb (RL) in transtibial amputees (TTAs), which improves socket fitting. However, the impact of the Overlay during functional tasks and on the comfort and pain felt in the RL is unknown. Methods: 8 TTAs participated in two evaluations, separated by two weeks. We measured compensatory strategies (CS) using spatio-temporal parameters and three-dimensional lower limb kinematics and kinetics during gait and sit-to-stand (STS) tasks. During each visit, the participant carried out our protocol while wearing the Overlay and prosthetic folds (PFs), the most common solution to VV. Between each task, comfort and pain felt were assessed using visual analog scales. Results: While walking, the cadence with the Overlay was 105 steps/min, while it was 101 steps/min with PFs (p = 0.021). During 35% and 55% of the STS cycle, less hip flexion was observed while wearing the Overlay compared to PFs (p = 0.004). We found asymmetry coefficients of 13.9% with the Overlay and 17% with PFs during the STS (p = 0.016) task. Pain (p = 0.031), comfort (p = 0.017), and satisfaction (p = 0.041) were better with the Overlay during the second visit. Conclusion: The Overlay’s impact is similar to PFs’ but provides less pain and better comfort.