Prosthetic Foot Stiffness Modulation for Below Knee Amputation

(OSA Trial)

Overseen By Elise Campbell

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: Seattle Institute for Biomedical and Clinical Research

Disqualifiers: Gait disorders, Skin irritation, Assistive device use

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 2

Duration: 3 hours

20 Participants Needed

Trial Summary

What is the purpose of this trial?

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).

Will I have to stop taking my current medications?

The trial information does not specify whether you need to stop taking your current medications.

What data supports the effectiveness of the treatment Automatic Prosthetic Foot Stiffness Modulation for below-knee amputation?

Research shows that adjusting the stiffness of prosthetic feet can reduce the energy needed for walking and lessen the strain on the knee of the intact leg. This suggests that automatic stiffness modulation could improve walking comfort and reduce joint stress for people with below-knee amputations. ^{1 2 3 4 5}

Is the prosthetic foot stiffness modulation generally safe for humans?

Research on prosthetic foot stiffness modulation, including the Variable Stiffness Foot (VSF), has focused on its mechanical effects and gait improvements, but specific safety data is not detailed in the available studies. However, a stepwise safety protocol for lower limb prosthetic risk management has been proposed to ensure safety during testing and training, which suggests that safety is a priority in the development and evaluation of these devices. ^{4 6 7 8 9}

How does the Automatic Prosthetic Foot Stiffness Modulation treatment differ from other treatments for below-knee amputation?

The Automatic Prosthetic Foot Stiffness Modulation treatment is unique because it adjusts the stiffness of the prosthetic foot in real-time based on muscle signals, allowing for more natural movement and improved walking efficiency. This approach contrasts with traditional prosthetic feet, which have a fixed stiffness and cannot adapt to different walking conditions or user needs. ^{2 3 5 7 10}

Research Team

Glenn Klute, PhD

Principal Investigator

US Department of Veterans Affairs

Richard Neptune, PhD

Principal Investigator

The University of Texas at Austin

Eligibility Criteria

This trial is for individuals with below knee amputations. Participants should be able to perform daily activities and must not have any additional conditions that could affect balance or require a specific prosthesis stiffness outside the study's range.

Inclusion Criteria

It has been over a year since my amputation.

I can walk on a treadmill.

I have had one leg amputated below the knee.

Exclusion Criteria

I have a condition other than amputation that affects my ability to walk.

I have skin irritation or injury on my amputated limb.

I use a device like a cane or walker to help me walk.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Fitting and Adjustment

Participants are fitted with a novel prosthesis and adjustments are made to the pylon length as needed

1 week

1 visit (in-person)

Treatment

Participants perform nine ambulatory activities with different prosthetic foot stiffness levels to optimize balance control

3 hours

1 visit (in-person)

Follow-up

Participants are monitored for safety and effectiveness after treatment

4 weeks

Treatment Details

Interventions

• Automatic Prosthetic Foot Stiffness Modulation

Trial Overview The trial tests how different levels of prosthetic foot stiffness impact balance during everyday activities. It compares the person's usual foot stiffness with two variations: one stiffer and one less stiff, across nine common tasks.

Participant Groups

Group I: Walking up an 8% slope at self-selected speed Experimental Treatment 3 Interventions

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 II: Walking on uneven terrain at self-selected speed Experimental Treatment 3 Interventions

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 III: Walking on 0% slope at self-selected speed while hand carrying a 5 kg load on their prosthetic side Experimental Treatment 3 Interventions

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 IV: Walking on 0% slope at self-selected speed Experimental Treatment 3 Interventions

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 V: Walking on 0% slope at 15% slower than self-selected speed Experimental Treatment 3 Interventions

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 VI: Walking on 0% slope at 15% faster than self-selected speed Experimental Treatment 3 Interventions

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 VII: Walking down an 8% slope at self-selected speed Experimental Treatment 3 Interventions

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 VIII: Walking around a 2-meter diameter circle with the prosthesis on the outside of the circle Experimental Treatment 3 Interventions

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 IX: Walking around a 2-meter diameter circle with the prosthesis on the inside of the circle Experimental Treatment 3 Interventions

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.

Who Is Running the Clinical Trial?

Seattle Institute for Biomedical and Clinical Research

Lead Sponsor

Trials

55

Recruited

13,700+

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

Collaborator

Trials

2,103

Recruited

2,760,000+

Findings from Research

A robotic prosthetic foot emulator (PFE) can accurately replicate the effective ankle stiffness of various commercial prosthetic forefeet, achieving an average accuracy within 1% of the actual feet tested.

This technology allows prosthesis users to trial different foot types based on their mechanical characteristics, potentially improving the decision-making process for prosthetic foot selection and enhancing user satisfaction.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Emulating the Effective Ankle Stiffness of Commercial Prosthetic Feet Using a Robotic Prosthetic Foot Emulator. Halsne, EG., Curran, CS., Caputo, JM., et al.[2022]

A structured protocol for testing lower limb prostheses emphasizes safety, requiring users to meet specific graded safety levels before progressing to more challenging environments.

This approach aims to reduce the risk of falls and injuries, thereby enhancing user confidence and overall experience with active prosthetic legs.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Design of a stepwise safety protocol for lower limb prosthetic risk management in a clinical investigation. Thesleff, A., Ahkami, B., Anderson, J., et al.[2022]

References

1. United States pubmed.ncbi.nlm.nih.gov

Emulating the Effective Ankle Stiffness of Commercial Prosthetic Feet Using a Robotic Prosthetic Foot Emulator. [2022]

2. United States pubmed.ncbi.nlm.nih.gov

Optimization of prosthetic foot stiffness to reduce metabolic cost and intact knee loading during below-knee amputee walking: a theoretical study. [2022]

3. United States pubmed.ncbi.nlm.nih.gov

Real-Time Interface Algorithm for Ankle Kinematics and Stiffness From Electromyographic Signals. [2021]

4. France pubmed.ncbi.nlm.nih.gov

Comparing forefoot and heel stiffnesses across commercial prosthetic feet manufactured for individuals with varying body weights and foot sizes. [2023]

5. United States pubmed.ncbi.nlm.nih.gov

Altering prosthetic foot stiffness influences foot and muscle function during below-knee amputee walking: a modeling and simulation analysis. [2022]

6. United States pubmed.ncbi.nlm.nih.gov

Prosthetic forefoot and heel stiffness across consecutive foot stiffness categories and sizes. [2022]

7. United States pubmed.ncbi.nlm.nih.gov

Sensitivity of lower-limb joint mechanics to prosthetic forefoot stiffness with a variable stiffness foot in level-ground walking. [2023]

8. United States pubmed.ncbi.nlm.nih.gov

Design of a stepwise safety protocol for lower limb prosthetic risk management in a clinical investigation. [2022]

9. United States pubmed.ncbi.nlm.nih.gov

Knee Swing Phase Flexion Resistance Affects Several Key Features of Leg Swing Important to Safe Transfemoral Prosthetic Gait. [2021]

10. Netherlands pubmed.ncbi.nlm.nih.gov

Sensitivity of biomechanical outcomes to independent variations of hindfoot and forefoot stiffness in foot prostheses. [2022]