Automatic Prosthetic Foot Stiffness Modulation to Improve Balance (OSA)

Seattle Institute for Biomedical and Clinical Research

Status

Enrolling

Conditions

Lower Limb Amputation Below Knee

Treatments

Device: Two categories less stiff than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories stiffer than the as-prescribed stiffness

Study type

Interventional

Funder types

Other

NIH

Identifiers

NCT06711588

1R01HD111514-01A1 (U.S. NIH Grant/Contract)

1817327

Details and patient eligibility

About

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).

Full description

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.

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

Enrollment

20 estimated patients

Sex

All

Ages

18 to 70 years old

Volunteers

No Healthy Volunteers

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.)

Trial design

Primary purpose

Basic Science

Allocation

Randomized

Interventional model

Single Group Assignment

Masking

Double Blind

20 participants in 9 patient groups

Walking on 0% slope at self-selected speed

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness

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

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness

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

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness

Walking up an 8% slope at self-selected speed

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness

Walking down an 8% slope at self-selected speed

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: 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

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness

Walking on uneven terrain at self-selected speed

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: 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

Experimental group

Description:

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.

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: 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

Experimental group

Description:

Treatment:

Device: Two categories stiffer than the as-prescribed stiffness

Device: As-prescribed stiffness

Device: Two categories less stiff than the as-prescribed stiffness