An Automatically Adjusting Prosthetic Socket for People With Transtibial Amputation

An Automatically-adjusting Prosthetic Socket for People With Transtibial Amputation

People with leg amputations often experience daily changes in the size (volume) of their residual limb. These daily changes can cause a prosthesis to fit poorly. They can also cause limb problems like pain or skin breakdown. Prosthetic socket systems that accommodate limb volume changes can help address these issues, but they require users to make adjustments throughout the day. The aim of this research is to create a system that will automatically adjust the fit of the socket and create a well-fitting prosthesis for people with leg amputations who experience volume fluctuations when using their prosthesis.

Study Overview

• Status: Recruiting
• Conditions: Lower Limb Amputation Below Knee (Injury); Diurnal Residual Limb Fluid Volume Fluctuation
• Intervention / Treatment: Device: Auto Adjusting Prosthesis

Detailed Description

he goal of this research is to determine if an automatic-adjusting prosthetic socket produces better participant outcomes than a manually-adjusting socket or a standard of care control in people with trans-tibial limb amputation. Prosthesis users will wear each socket configuration for 2 weeks. Endpoints will include self-reported comfort, convenience, and fatigue; residual limb health; wear time; activities time; and variability in socket fit. Each condition will be tested separately in a cross-over study design, including a 2-week washout period between the conditions. This aim will use a crossover randomized trial to evaluate the importance of the socket condition The three test conditions will be (1) an automatic-adjusting socket; and (2) a manual-adjusting socket; and (3) a standard of care (adjust socks) control in which socket adjustment is locked. Participants will test each of these three conditions in a random order. There will be a 2-week washout period between test conditions. Participation will begin with an initial sessions where the researchers will evaluate inclusion criteria, collect demographic information, conduct a brief bioimpedance test and thermal imaging test, scan the participant's existing socket and instrument the participant's traditional socket with a monitor to collect activity data for 2 weeks while the investigational prosthesis is fabricated. When the investigational prosthesis is prepared, participants will return to the lab. Self-report questionnaires will be completed, and residual limb health assessed. The participant will be trained on how to operate the socket. The socket will be set to the first condition (order of conditions randomly selected). After using the socket for 3 to 5 days, the researchers will go to the participant's location for a check-in visit. The participant will have an opportunity to ask questions and discuss any issues they are having with the socket. The researchers will make sure the socket is functioning properly. After 2 weeks total, participants will return to the lab and complete self-report questionnaires and have their residual limb health assessed. They will participate in an interview about their experience wearing the socket. After a 2-week washout period, they will conduct the same procedure wearing another socket condition. After another 2-week washout period, they will conduct the same procedure wearing the remaining socket condition.

• Study Type: Interventional
• Enrollment (Estimated): 100
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Katheryn Allen, CPO; Phone Number: 206-390-0228; Email: kate@allyn.org
• Study Contact Backup: Name: Tessa S Viljamaa; Email: tessasv@uw.edu

Study Locations

• United States
  • Washington
    • Seattle, Washington, United States, 98105
      • Recruiting
      • William H. Foege Hall
      • Contact: Katheryn Allyn; Phone Number: 206-390-0228; Email: kate@allyn.org

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes

Description

• 18 years or older
• Unilateral or bilateral trans-tibial amputation at least 12 months prior
• Have a limb of length 9 cm or greater
• Are capable of at least 5 minutes of continuous walking
• Are capable of at least 1 hour of intermittent walking
• Regularly use a definitive prosthesis with a pin-lock suspension system and no or few pads
• Have adequate sensation to verbalize a socket that is too large or too small to be tolerated
• Do not regularly use assistive devices (e.g., cane, walker) for ambulation
• Do not have open wounds on their residual limb at the time of enrollment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Focus Group Testing; Focus group testing of key-fob device to control adjusting socket system
Experimental: In-Lab, Crossover Study; Testing of auto-adjusting algorithm in-lab. Participants will carry out a structured protocol wearing the socket in all modes. Order will be randomly assigned.	Device: Auto Adjusting Prosthesis; Participants will test the auto adjusting prosthesis. The prosthesis will be able to move up to 3 panels built into the socket walls to expand or tighten the socket's fit. The auto adjustments will take place during periods of sitting, standing, or walking. Manual adjustments will also be possible either via the researcher controlling the prosthesis or via the key fob developed in the first aim.
Experimental: Out-of-Lab Crossover Study; Evaluate socket performance in user free-living environments. Participants will use the prosthesis in all modes by end of study, order will be randomly assigned.	Device: Auto Adjusting Prosthesis; Participants will test the auto adjusting prosthesis. The prosthesis will be able to move up to 3 panels built into the socket walls to expand or tighten the socket's fit. The auto adjustments will take place during periods of sitting, standing, or walking. Manual adjustments will also be possible either via the researcher controlling the prosthesis or via the key fob developed in the first aim.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Socket Comfort Score	Participants in Aim 2 and Aim 3 will test various configurations of the auto adjustment algorithm. Socket comfort score will be asked at various time points during testing, and overall changes in this metric will be calculated from the start and end of session.	through study completion, an average of 1 year
Integral Absolute Error of Control System	Calculated error will be measured through each test session, both in and out of lab.	through study completion, an average of 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percent change in Limb Fluid Volume	Participant's limb fluid volume will be measured during the structured in-lab protocol (Aim 2), and changes will be compared against an initial reference point of activity during which no interventions will take place.	through study completion, an average of 1 year
Residual limb health	Data collected using a standard skin assessment protocol and an IR imaging camera will be used. For IR data, thermal recovery time will be calculated and a difference map of TRT between the beginning and end test condition created	Baseline and through study completion, an average of 1 year
Prosthesis wear time	Socket fit sensor data will be used	Up to 12 weeks
Time of activities	Durations of walking, standing, sitting, sitting partially doffed, and doffed will be calculated for each day, using socket fit sensor and pin sensor data	Up to 12 weeks
Variability in socket fit	This will be calculated from socket sensor SFM data	Up to 12 weeks

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of manual socket size adjustments	This will be calculated using motor displacement data	Up to 12 weeks
Participant socket preference and qualitative interview responses	Information from the end of study interview will be tabulated	Through study completion, an average of 1 year

Collaborators and Investigators

• Sponsor: University of Washington
• Collaborators: Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)
• Investigators: Principal Investigator: Joan E Sanders, PhD, University of Washington

Study record dates

Study Major Dates

• Study Start (Actual): October 18, 2021
• Primary Completion (Estimated): March 1, 2027
• Study Completion (Estimated): June 1, 2027

Study Registration Dates

• First Submitted: October 20, 2021
• First Submitted That Met QC Criteria: November 5, 2021
• First Posted (Actual): November 18, 2021

Study Record Updates

• Last Update Posted (Actual): May 7, 2026
• Last Update Submitted That Met QC Criteria: May 5, 2026
• Last Verified: March 1, 2026

More Information

Terms related to this study

• Keywords: amputee; prosthetic
• Additional Relevant MeSH Terms: Wounds and Injuries
• Other Study ID Numbers: STUDY00009418; 1R01HD103815-01A1 (U.S. NIH Grant/Contract)

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No