Single-Subject Research Design on 3D-Printed Prosthetic Sockets

A 3D-Printed Prosthesis Portable Station: The Vancouver Limbkit Project

The goal of this single-subject research design (clinical trial) is to assess the functionality of the 3D printed prostheses and to compare them to the existing prostheses in terms of mobility, balance, utility, and comfort. Participants who have a unilateral or bilateral transtibial amputation wear their existing prosthesis for roughly 3 weeks, followed by 3 weeks wearing a 3D printed prosthesis. The research assistants collect data throughout each period remotely, with the exception of one in-person visit to participants' homes to prepare the setting for the virtual evaluation sessions.

Once a participant is recruited and consent is obtained, Phase (A) begins with the research assistants conducting one home visit with the participant. This visit sets up the performance-based outcome measures, provides instructions for performing the tests, explains how to complete the online surveys, and clarifies how to take the video recordings. The research assistants distribute the Sociodemographic and Clinical Characteristics questionnaire to the participant via the UBC Qualtrics platform.

During Phase (A), the participant wears their definitive prosthesis and is remotely evaluated up to three times per week for three weeks. At the end of Phase (A), the participant receives an online self-reported survey to measure the utility of using the definitive prosthesis.

The participant then attends their prosthetic clinic to have measurements and a scan of their residual limb taken for the 3D printed prosthesis. The prosthetists use the "Comb" mobile scanner application, and the scans of the participants are securely stored and de-identified to maintain the confidentiality of the participants' information through the HIPAA-compliant Comb portal. The research assistant prints the prosthesis, which includes implanting a thermal sensor into the prosthesis to monitor the wear time. The participant visits the prosthetic clinic a second time to have the 3D printed prosthesis fitted by the relevant prosthetist in the team. The prosthetist ensures the new prosthesis is properly fitted and appropriate for use before allowing the participant to go home with it.

In Phase (B), the participant uses the 3D-printed prosthesis for three weeks and conducts the same outcome measures. At the end of Phase (B), the participant receives an online self-reported survey to measure the utility of using the 3D printed prosthesis.

Participants drop off the 3D-printed prostheses at their prosthetic clinics at the end of the study. Then the RA collects all the 3D printed prostheses to keep them in a locked cabinet in the principal investigator's office at the University of British Columbia.

The participant then has a one-to-one virtual semi-structured interview to explore their experiences with the 3D printed prosthesis.

A separate focus group is conducted with prosthetists involved in this study to obtain their feedback and suggestions regarding the Limbkit.

Inclusion Criteria:

• are adults 19+ years,
• have a unilateral or bilateral transtibial amputation,
• have an existing definitive prosthesis,
• use their definitive prosthesis two or more consecutive hours per day,
• have no wounds on the residual limb.

Exclusion Criteria:

• are unable to adequately complete self-report measures or communicate well enough to participate in the end of project interview,
• have bilateral upper extremity amputations,
• have poorly controlled comorbidities (e.g., unstable diabetes, advanced heart problems)