September/ October 2018 Research: Mobile Technology: Empowering Prosthesis Wearers To Problem-Solve Socket Fit Issues

Mobile Technology: Empowering Prosthesis Wearers To Problem-Solve Socket Fit Issues

By Daniel J. Lee, PT, DPT, GCS

The Problem

A client is in the early stages of prosthesis wearing. The prosthetist has educated the client on how to self-manage the residual limb/socket interface, ensured that the fit of the socket is correct, and instructed the client to follow up immediately if the prosthesis is uncomfortable or fitting poorly. Despite best efforts by the prosthetist, the client ultimately is dependent on himself or herself to ensure that he or she is donning, managing volume fluctuations, and achieving a congruent fit of the prosthetic socket on the residual limb when outside of the clinic.

The client may find that because of natural changes in the residual limb’s volume throughout the day, he or she  may need to add or subtract sock ply or adjust the suspension mechanism to maintain the congruent fit. While the client has been educated on how to perform this function, it is a complex task that requires practice, problem-solving skills, knowledge, and the ability to recognize when the assistance of the prosthetist is needed.

While some clients may easily adapt to the process of problem solving the fit of the prosthesis, others will struggle. Some may attempt to solve fit issues without an organized and deliberate approach, which can result in poor suspension or possible skin breakdown. Others may not wear the prosthesis at all and call on the prosthetist instead of performing his or her role in self-management and problem solving, decreasing both the utilization of the prosthesis and the prosthetist’s productivity. In either scenario, the result is antithetical to functionally implementing the prosthesis and can create a barrier to independence.

The Solution

A simple-to-use, client-centered mobile application that guides the prosthesis wearer in the problem solving of common prosthetic socket fit issues for most suspension types can help solve the problem.

With such a mobile app, the client creates an account, selects his or her level of amputation and suspension type, then navigates the one-press interface to explore solutions to frequently encountered issues experienced with the prosthesis. Major problems are categorized in easy-to-understand terms like, “My prosthesis is fitting loosely,” or, “My prosthesis is fitting too tight.” Under each major problem, individual issues and their corresponding solution sets are presented in a hierarchical and logical order, from simplest to most complex, specific to each suspension type. The client can navigate each issue and, based on a “Yes” or “No” response to the question, be presented with a specific solution to his or her problem. If the client tries the solution (e.g., adds a one-ply sock) and it works, he or she is presented with a “Problem Solved” screen, and the fit should be comfortable and congruent. If the solution does not meet the client’s needs, he or she will be presented with a finite number of other potential solutions to try before finally being presented with an instructional message to contact a prosthetist as the client is unable to problem-solve the fit issue with the app alone.

The app not only empowers the prosthesis wearer to solve problems within his or her control, it also encourages communication with the prosthetist in the case that the client cannot determine a solution on his or her own. It is believed that the app can reduce client frustration, improve communication, and ultimately improve outcomes after an individual receives a prosthesis.


To understand if this mobile app interface is usable and acceptable to prosthesis wearers, a multiphase testing protocol was performed.

First, a paper form of the decision trees was developed and validated. The decision trees provided the content for the mobile app and served as a comparison for the usability and acceptability testing. More on the decision trees can be found in a 2017 Disability & Rehabilitation publication.1 Once the decision tree content was established, a cross-platform mobile app was developed with an interface accessible to all age groups.

After beta testing the app for functionality, the next phase was to assess usability and acceptability. A total of 30 participants, all lower-limb prosthesis wearers, performed six trials of step-matched navigation on the app and the paper versions of the decision trees. Usability was measured by two criteria: technical effectiveness (number of errors made while navigating the tool) and efficacy (amount of time spent navigating). Acceptability was determined through Likert-like questions and a semistructured interview.


The mobile app was found to be significantly more usable and acceptable when compared to the paper-based decision trees. When using the app to navigate the scenarios, there were fewer errors committed and less time to complete the navigation (see Figure 1).

While both tools were found to be highly acceptable, the mobile app version was found to be easier to use, to be less confusing to navigate, and to have a higher overall user experience (see Figure 2).

Qualitative analysis of the semistructured interviews resulted in three themes:

1) The paper-based decision trees were organized.

2) The paper-based decision trees were difficult to navigate.

3) The mobile app was simple to use and navigate.


Obtaining and maintaining a comfortable fit of the prosthesis is a priority of the prosthetist; however, despite best educational interventions, the client may experience issues that require problem solving outside of the clinic. The mobile app is an easy-to-navigate interface for a prosthesis wearer to employ in problem-solving fit issues while being directed to his or her prosthetist in the event a comfortable fit is not achieved.

This article is a summary of a manuscript that will be published in an upcoming issue of the Journal of Prosthetics & Orthotics under the title, “Self-Management Problem-Solving Tools for Lower-Limb Prosthesis Wearers: Evaluating Technical Effectiveness, Efficiency, and Acceptability.” The study was funded by the University of Hartford’s College of Education, Nursing, and Health Professions.

Daniel J. Lee, PT, DPT, GCS, is a board-certified clinical specialist in geriatrics through the American Board of Physical Therapy Specialties. He is an assistant professor at the University of Hartford in the Department of Rehabilitation Sciences, where he is dual appointed to both the Doctor of Physical Therapy and Masters of Prosthetics and Orthotics programs. Lee may be contacted at


  1. Daniel JL, Veneri DA. Development and Acceptability Testing of Decision Trees for Self-Management of Prosthetic Socket Fit in Adults With Lower-Limb Amputation. Disability and Rehabilitation. 2018; 40(9):1066-1071. DOI: 10.1080/09638288.2017.1286694