Automatic Prosthetic Foot Stiffness Modulation to Improve Balance

NCT ID: NCT06711588

Last Updated: 2025-12-17

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

RECRUITING

Clinical Phase

NA

Total Enrollment

20 participants

Study Classification

INTERVENTIONAL

Study Start Date

2024-12-19

Study Completion Date

2026-06-30

Brief Summary

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The goal of this clinical trial is to identify prosthesis stiffness that optimizes balance control in individuals with below knee amputations. The main question this clinical trial will answer is:

• Is there an optimal stiffness that improves balance control for specific ambulatory activities and users? Participants will wear a novel prosthesis assembled with three prosthetic feet with a range of stiffness levels: each individual's clinically-prescribed foot stiffness and ± two stiffness categories. While wearing the study prostheses, participants will perform nine ambulatory activities of daily living (walking at different speeds, turning, ramp ascent/descent, while carrying a load, and while walking on uneven terrain).

Detailed Description

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Individuals with lower limb amputations are at higher risk of falling compared to able-bodied and other clinical populations and are more likely to sustain life-altering injuries. The higher fall risk is primarily due to the loss of the muscles crossing the ankle, which are critical to maintaining balance control. Prosthetic devices are designed to provide appropriate stiffness for needed stability and support. While research has shown the optimal stiffness to maintain balance varies across ambulatory activities (e.g., straight walking versus turning), most clinically prescribed prosthetic devices are passive and only provide a fixed stiffness level. The one commercially available, powered prosthetic ankle-foot has not been shown to restore balance control. Thus, a prosthetic device that actively adjusts ankle stiffness across different ambulatory activities is critically needed to advance the field and improve balance control for those with lower-limb amputations. The goal of this clinical trial is to identify prosthesis stiffness that optimizes balance control in individuals with below knee amputations as they perform typical ambulatory activities of daily living. By matching the ankle stiffness to the task requirements, we believe we will significantly improve balance control and decrease fall risk for those with lower-limb amputations.

Each participant will be fit with a novel prosthesis that includes a low-profile prosthetic foot whose stiffness category will be determined by their body weight and activity level (standard clinical practice), a prosthetic foot whose stiffness category is two categories stiffer, and another whose stiffness is two categories less stiff. Participants will continue to use their existing prosthetic socket and suspension system, but their pylon length will be adjusted as needed. While wearing the different study prostheses in randomized order, nine ambulatory activities will be performed motion capture laboratory.

1. Walking on level ground at self-selected speed.
2. Walking on level ground at 15% slower than self-selected speed.
3. Walking on level ground at 15% faster than self-selected speed.
4. Walking up an 8% slope at self-selected speed.
5. Walking down an 8% slope at self-selected speed.
6. Walking on level ground at self-selected speed while carrying a 5 kg load in one hand on their prosthetic side.
7. Walking on level but uneven terrain at self-selected speed.
8. Walking a 2-meter diameter circle at self-selected speed with the prosthetic side on the inside of the circle.
9. Walking a 2-meter diameter circle at self-selected speed with the prosthetic side on the outside of the circle.

Ambulatory activities 1 through 6 will be performed on an instrumented treadmill. The load to be carried in activity 6 will be configured as a grocery bag with handles. Activity 7 will be performed on a rocky terrain treadmill. Activities 8 and 9 will be performed overground across five force plates embedded in the laboratory floor while following the outline of a 2-meter diameter circle. Rest breaks during all activities will be provided as needed.

The data from these experiments will be used to calculate the peak-to-peak range of the frontal plane whole-body angular momentum (a measure of balance control). We hypothesize that an optimal user-specific stiffness profile exists that maximizes balance control (i.e., minimizes the peak-to-peak range of frontal plane whole-body angular momentum over the gait cycle) for each ambulatory activity.

Conditions

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Lower Limb Amputation Below Knee

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

SINGLE_GROUP

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

DOUBLE

Participants Investigators

Study Groups

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Walking on 0% slope at self-selected speed

All participants will walk on a treadmill, in a straight line, on a 0% slope, at their self-selected walking speed determined while walking overground.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking on 0% slope at 15% slower than self-selected speed

All participants will walk on a treadmill, in a straight line, on a 0% slope, at a speed that is 15% slower than their self-selected walking speed determined while walking overground.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking on 0% slope at 15% faster than self-selected speed

All participants will walk on a treadmill, in a straight line, on a 0% slope, at a speed that is 15% faster than their self-selected walking speed determined while walking overground.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking up an 8% slope at self-selected speed

All participants will walk on a treadmill, in a straight line, up an 8% slope, at their self-selected walking speed determined while walking overground up an 8% slope.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking down an 8% slope at self-selected speed

All participants will walk on a treadmill, in a straight line, down an 8% slope, at their self-selected walking speed determined while walking overground up an 8% slope.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking on 0% slope at self-selected speed while hand carrying a 5 kg load on their prosthetic side

All participants will walk on a treadmill, in a straight line, on a 0% slope, at their self-selected walking speed determined while walking overground, while carrying a 5 kg load in one hand on their prosthetic side.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking on uneven terrain at self-selected speed

All participants will walk on an uneven terrain treadmill, in a straight line, on a 0% slope, at their self-selected walking speed determined while walking on the uneven terrain treadmill.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking around a 2-meter diameter circle with the prosthesis on the inside of the circle

All participants will walk overground while following the outline of a 2-meter diameter circle, at their self-selected walking speed determined while walking around the circle, with their prosthetic limb on the inside of the circle.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Walking around a 2-meter diameter circle with the prosthesis on the outside of the circle

All participants will walk overground while following the outline of a 2-meter diameter circle, at their self-selected walking speed determined while walking around the circle, with their prosthetic limb on the outside of the circle.

Group Type EXPERIMENTAL

As-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Two categories stiffer than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Two categories less stiff than the as-prescribed stiffness

Intervention Type DEVICE

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Interventions

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As-prescribed stiffness

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is determined by the person's body weight and activity level (standard clinical practice).

Intervention Type DEVICE

Two categories stiffer than the as-prescribed stiffness

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories stiffer than the as-prescribed stiffness.

Intervention Type DEVICE

Two categories less stiff than the as-prescribed stiffness

A novel prosthesis that includes a low-profile prosthetic foot whose stiffness category is two categories less stiff than the as-prescribed stiffness.

Intervention Type DEVICE

Eligibility Criteria

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Inclusion Criteria

* Unilateral transtibial (below-knee) amputation
* Been fit with a prosthesis and used it for at least 6 months
* Wear the prosthesis for 4 or more hours on average per day
* Be at least one-year post-amputation
* Able to walk on a treadmill

Exclusion Criteria

* Presence of disorder, pain, or injury other than amputation that interferes with gait
* Current skin irritation or injury on residual limb
* Use of an assistive device for walking (cane, walker, etc.)
Minimum Eligible Age

18 Years

Maximum Eligible Age

70 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Sponsors

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Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD)

NIH

Sponsor Role collaborator

Seattle Institute for Biomedical and Clinical Research

OTHER

Sponsor Role lead

Responsible Party

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Responsibility Role SPONSOR

Principal Investigators

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Glenn Klute, PhD

Role: PRINCIPAL_INVESTIGATOR

US Department of Veterans Affairs

Richard Neptune, PhD

Role: PRINCIPAL_INVESTIGATOR

The University of Texas at Austin

Locations

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VA Puget Sound Healthcare System

Seattle, Washington, United States

Site Status RECRUITING

Countries

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United States

Central Contacts

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Glenn K Klute, PhD

Role: CONTACT

206-277-6792

Elise Campbell

Role: CONTACT

206-277-6792

Facility Contacts

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Carlos Hernandez

Role: primary

206-764-2991

Other Identifiers

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1R01HD111514-01A1

Identifier Type: NIH

Identifier Source: secondary_id

View Link

1817327

Identifier Type: -

Identifier Source: org_study_id