Sub-Ischial Socket for Transfemoral Amputation and Lower Mobility

NCT05662982 | Completed FDA Device

• 3 other identifiers: STUDY00015284CDMRP-E03034.1aCDMRP-E03034.1b
• Study Type: interventional
• Target: 84
• Locations: 1 country
• Sites: 3

Brief Summary

The objective of this trial is to assess use and benefits of the subischial socket for persons with transfemoral amputation and lower mobility levels. Specifically, the investigators will evaluate whether the subischial socket improves comfort, socket wear time, mobility, participation, quality of life and satisfaction with device than the standard-of-care ischial containment socket.

Conditions

Transfemoral Amputation

Keywords

prosthesis; prosthetic socket

Outcome Measures

Primary Outcomes (1)

• Change in Socket Comfort Score (SCS)

  Single item self-report measure to rate average socket comfort on an 11-point scale where 0 represents the most uncomfortable socket fit participant can imagine and 10 represents the most comfortable socket fit participant can imagine. Participants will rate their socket comfort in general, and while sitting, standing, and walking.

  Change from week 12 to week 24 compared between Intervention and Reference Groups.

Secondary Outcomes (12)

• Temperature sensor

  Intervention group only: Baseline period weeks 0-12; Intervention period weeks 0-24.

• Step counter

  Intervention group only: Baseline period weeks 0-4; Intervention period weeks 0-4 and 20-24.

• Prosthesis Limb Users Survey-Mobility (PLUS-M)

  All participants: Baseline period weeks 0, 4, 8, 12; Intervention group: Intervention period weeks 4, 8, 12, 16, 20, 24; Reference group: Monitoring period weeks 4, 12, 20, 24.

• Activities-specific Balance Confidence (ABC) Scale

  All participants: Baseline period weeks 0, 4, 8, 12; Intervention group: Intervention period weeks 4, 8, 12, 16, 20, 24; Reference group: Monitoring period weeks 4, 12, 20, 24.

• Prosthesis Evaluation Questionnaire (PEQ) Residual Limb Health

  All participants: Baseline period weeks 0, 4, 8, 12; Intervention group: Intervention period weeks 0, 4, 8, 12, 16, 20, 24; Reference group: Monitoring period weeks 4, 12, 20, 24.

Other Outcomes (2)

• Amputee Mobility Predictor with Prosthesis (AMP-Pro)

  Intervention group only: Baseline period week 0; Intervention period weeks 0, 20.

• International Society for Prosthetics and Orthotics (ISPO) Minimum Data Set for lower-limb prosthesis users involved Research Studies

  Intervention group: Baseline period week 0; Intervention period week 0. Reference Group: Baseline period week 0.

Study Arms (2)

Intervention Group

EXPERIMENTAL

Participants will be assessed for 12 weeks in their usual ischial containment socket before receiving a subischial socket to be worn and assessed for 24 weeks.

Device: Northwestern University Flexible Subischial Suction Socket (NU-FlexSIS)

Reference Group

NO INTERVENTION

Participants will be assessed for 40 weeks in their usual ischial containment socket. No intervention will be provided.

Interventions

Northwestern University Flexible Subischial Suction Socket (NU-FlexSIS) DEVICE

A custom-made prosthetic socket for transfemoral amputation that consists of proximal trimlines that do not interact with the pelvis.

Intervention Group

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Speak and read English;
• Provision of signed and dated informed consent form;
• Stated willingness to comply with all study procedures and availability for the duration of the study;
• All sexes and genders age 18 years and older;
• Have a unilateral transfemoral or knee disarticulation amputation and have used a prosthesis for 1 year or more;
• Be classified by their prosthetist as being a Medicare Functional Classification Level of K2 (limited community ambulator);
• Have never worn a sub-ischial socket;
• Current IC socket and prosthesis must be well fitting and maintained; current socket must have pelvic weightbearing and/or containment;
• Participant has no plans to change the knee or foot in the next 10 months;
• Willingness to adhere to the monitoring and new socket regimen;
• Have sufficient upper limb function to don liner and change sensors;
• Access to necessary resources for participating in the study (i.e., computer, smartphone, internet access, telephone):
• Be a Veteran (VA site only).

You may not qualify if:

• Have a femoral length \<5 inches;
• Have a known silicone allergy;
• Are unable to don or tolerate wearing a compressive liner;
• Loss of metatarsal heads on contralateral limb;
• Active malignancy;
• Pregnancy;
• Polytrauma that affects functional ability beyond that of a unilateral transfemoral amputation.

Sponsors & Collaborators

• University of Washington: lead
• Congressionally Directed Medical Research Programs: collaborator

Study Sites (3)

Minneapolis VA Health Care System

Minneapolis, Minnesota, 55417, United States

Location

Hanger Institute for Clinical Research and Education

Houston, Texas, 78758, United States

Location

University of Washington

Seattle, Washington, 98195, United States

Location

Related Publications (4)

• Fatone S, Caldwell R. Northwestern University Flexible Subischial Vacuum Socket for persons with transfemoral amputation-Part 1: Description of technique. Prosthet Orthot Int. 2017 Jun;41(3):237-245. doi: 10.1177/0309364616685229. Epub 2017 Jan 17.

  PMID: 28094686 BACKGROUND

• Caldwell R, Fatone S. Technique modifications for a suction suspension version of the Northwestern University Flexible Sub-Ischial Vacuum socket: The Northwestern University Flexible Sub-Ischial Suction socket. Prosthet Orthot Int. 2019 Apr;43(2):233-239. doi: 10.1177/0309364618798869. Epub 2018 Sep 17.

  PMID: 30223715 BACKGROUND

• Fatone S, Caldwell R, Angelico J, Stine R, Kim KY, Gard S, Oros M. Comparison of Ischial Containment and Subischial Sockets on Comfort, Function, Quality of Life, and Satisfaction With Device in Persons With Unilateral Transfemoral Amputation: A Randomized Crossover Trial. Arch Phys Med Rehabil. 2021 Nov;102(11):2063-2073.e2. doi: 10.1016/j.apmr.2021.05.016. Epub 2021 Jun 29.

  PMID: 34214499 BACKGROUND

• Fatone S, Stine R, Caldwell R, Angelico J, Gard SA, Oros M, Major MJ. Comparison of Ischial Containment and Subischial Sockets Effect on Gait Biomechanics in People With Transfemoral Amputation: A Randomized Crossover Trial. Arch Phys Med Rehabil. 2022 Aug;103(8):1515-1523. doi: 10.1016/j.apmr.2022.02.013. Epub 2022 Mar 13.

  PMID: 35296398 BACKGROUND

Study Officials

• Stefania Fatone, PhD

  University of Washington

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NON RANDOMIZED
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Professor, School of Medicine

Model Details: Two independent groups will be assessed longitudinally over 40 weeks: one group will be assessed using only the standard of care ischial containment socket and the other group will receive the subischial socket.

Study Record Dates

• First Submitted: December 12, 2022
• First Posted: December 23, 2022
• Study Start: March 1, 2023
• Primary Completion: November 30, 2025
• Study Completion: November 30, 2025
• Last Updated: December 15, 2025

Record last verified: 2025-12

Data Sharing

• IPD Sharing: Will share
• Shared Documents: STUDY PROTOCOL, SAP, ICF
• Time Frame: Data will be shared no later than the acceptance for publication of the main findings from the final dataset.
• Access Criteria: ResearchWorks creates persistent URLs that will not change over time. A DOI can also be created. The URL or DOI will be included with all publications arising from this trial.

Locations

US (3)