Northwestern University Feinberg School of Medicine

Northwestern University Prosthetics-Orthotics Center

No Longer Smooth: Introducing Striations into Prosthetic Socket Construction to Improve Suspension, Rotation, Fit and Comfort

Principal Investigator: Stefania Fatone, PhD, BPO(Hons)

Co-Investigators: Steven A. Gard, PhD, Rebecca Stine, MS, Marc Applebaum, MD (Jesse Brown VA Medical Center)

Collaborators: Tracy Slemker, CPO, Brad Poziembo, LP, Prosthetic Design Inc. (PDI) 

Other Study Staff: Lilly Tran, MS; Julia Quinlan, PhD, Jessica Yohay, BS

Status: In Progress 

Acknowledgment: 
The U.S. Army Medical Research Acquisition Activity, 820 Chandler Street, Fort Detrick MD 21702-5014 is the awarding and administering acquisition office. This work is supported by the Office of the Assistant Secretary for Health Affairs, through the Neuromusculoskeletal Injuries Research Award under Award No. W81XWH-16-1-0485. Opinions, interpretations, conclusions and recommendations are those of the author and are not necessarily endorsed by the U.S. Department of Defense. 

Introduction

Conventional prosthetic sockets are typically smooth on the inner surface, which may cause the prosthesis to slide or rotate on the residual limb. The prosthetic sockets to be investigated for this study are textured on the inside and may prevent relative movement between the prosthesis and the residual limb. Hence, this study will investigate a new design in prosthetic socket that may be more comfortable and enable greater control by the prosthesis user.

Objective/Hypothesis

The objective of this pre-clinical research project is to investigate the effect of different types of inner surface texturing on the suspension, rotation, fit, and comfort of prosthetic sockets. We hypothesize that horizontal striations will improve suspension while vertical striations will help control transverse plane rotation. It is possible that in combination, both suspension and rotation may be improved. However, striations may vary in either direction in depth and pattern and it remains unknown what combinations might maximize suspension and rotation benefits without compromising fit, comfort and durability.

Study Design

This project will utilize an existing SQUIRT-Shape Rapid Prototyping System to construct sockets inexpensively with varying types of texturing (See figure).

Sockets with varying types of texturing

Specific aims will
(1) test the force needed to displace the socket longitudinally and rotationally;
(2) test the coefficient of friction, tensile and static strength of sockets with different texturing patterns; and
(3) test the comfort and fit of textured sockets on Veterans with transtibial amputation.

The first two aims use various bench-top tests to develop an understanding of the mechanical properties and potential benefits of textured sockets as compared to conventional smooth thermoformed sockets. The last aim will assess the socket fit and comfort of textured sockets that perform well in aims 1 and 2 on five Veterans with transtibial amputation in a randomized, double-blind, cross-over study.