Exoskeleton Optimization for Peripheral Artery Disease

Overseen By Philippe Malcolm, PhD

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Nebraska

Disqualifiers: Neurological, Musculoskeletal, Cardiovascular, Pulmonary, others

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

Compensation: Varies

Number of Visits: Unknown

9 Participants Needed

What You Need to Know Before You Apply

What is the purpose of this trial?

Exoskeletons, wearable devices that assist with walking, can improve mobility in clinical populations. With exoskeletons, it is crucial to optimize the assistance profile. Recent studies describe algorithms (i.e., human-in-the-loop) to optimize the assistance profile with real-time metabolic measurements. The needed duration of current human-in-the-loop (HITL) algorithms range from 20 minutes to 1 hour which is longer than the average duration that most patients with peripheral artery disease (PAD) can walk. Because of this limited walking duration, it is often not possible for patients with PAD to reach steady-state metabolic cost, which makes these measurements are not useful for optimizing exoskeletons. In this study, investigators intend to develop and evaluate HITL optimization methods for exoskeletons and use the information to design and evaluate a portable hip exoskeleton. Shorter and more clinically feasible HITL optimization strategies based on experiments in healthy adults might allow utilizing these optimization strategies to become available for patient populations such as patients with PAD.

Do I need to stop my current medications for the trial?

The trial protocol does not specify if you need to stop taking your current medications. However, it mentions that your blood pressure, lipids, and diabetes should be stable for more than 6 weeks, which might imply continuing your current treatment.

Is the use of exoskeletons generally safe for humans?

Exoskeletons have been associated with some safety concerns, such as falls and injuries to the skin, tissue, and musculoskeletal system, as well as changes in blood pressure. However, strategies are being developed to minimize these risks, and regulatory bodies have approved some exoskeletons with special controls to ensure safety. More structured reporting and risk mitigation strategies are needed to enhance safety further. ^{1 2 3 4 5}

How does the exoskeleton treatment for Peripheral Artery Disease differ from other treatments?

The exoskeleton treatment for Peripheral Artery Disease is unique because it uses a wearable device to optimize walking by reducing energy costs and muscle activity, unlike traditional treatments that may focus on medication or surgery. This approach customizes assistance patterns to individual needs, improving walking efficiency and comfort. ^{6 7 8 9 10}

What data supports the effectiveness of the treatment Exoskeleton Optimization for Peripheral Artery Disease?

Research shows that optimizing exoskeleton assistance can significantly reduce the energy cost of walking, with one study reporting a 24.2% reduction in metabolic energy consumption. This suggests that similar optimization techniques could improve walking efficiency for patients with Peripheral Artery Disease. ^{6 7 11 12 13}

Who Is on the Research Team?

Philippe Malcolm, PhD

Principal Investigator

University of Nebraska

Are You a Good Fit for This Trial?

This trial is for individuals who can legally consent and have chronic leg pain due to poor blood flow (Peripheral Vascular Disease or Peripheral Arterial Disease), with specific measurements of blood flow, stable health conditions, and the ability to walk on a treadmill. They must fit certain physical criteria related to waist, thigh size, and length. Pregnant women and those with severe disease stages or other major health issues are excluded.

Inclusion Criteria

My blood pressure, cholesterol, and diabetes have been stable for over 6 weeks.

Ability to provide written consent

I meet the size requirements for the exoskeleton.

Exclusion Criteria

You are unable to understand or respond to visual signals because you are blind.

I have severe leg pain or tissue loss because of poor blood flow.

I recently had a blood clot or injury affecting my leg.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Habituation

Participants undergo a habituation session to the hip exoskeleton

1 session

Optimization

Optimization session to find the optimal actuation settings using a human-in-the-loop algorithm

1 session

Post-test

Post-test to compare different conditions after optimization

1 session

Follow-up

Participants are monitored for safety and effectiveness after the optimization

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

• Endurance evaluation
• Exoskeleton Variability Optimization

Trial Overview The study is testing a new way to adjust exoskeletons that might be quicker and more practical in clinical settings. It's being piloted on healthy subjects first before moving on to patients with peripheral artery disease. The focus is on how well these optimized exoskeletons help with endurance.

How Is the Trial Designed?

Group I: Optimal Assistance Pattern Experimental Treatment 1 Intervention

An optimization algorithm will change the assistance pattern on the hip exoskeleton during walking sessions and the optimal assistance pattern will be determined when gait variability is minimized.

Group II: Endurance Effectds Experimental Treatment 1 Intervention

Endurance of participants using ground reaction force (Bertec treadmill), walking speed (Bertec treadmill), indirect calorimetry (Cosmed), and motion capture (Vicon) will be determined.

Who Is Running the Clinical Trial?

University of Nebraska

Lead Sponsor

Trials

563

Recruited

1,147,000+

National Institute of General Medical Sciences (NIGMS)

Collaborator

Trials

315

Recruited

251,000+

Published Research Related to This Trial

A new method for optimizing exoskeleton assistance has been developed, which significantly reduces the metabolic energy cost of walking by 24.2% when using torque patterns on the ankle.

This optimization approach is effective across various walking conditions and can be tailored to individual users, enhancing the overall performance and efficiency of exoskeletons and active prostheses.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Human-in-the-loop optimization of exoskeleton assistance during walking. Zhang, J., Fiers, P., Witte, KA., et al.[2018]

A specific assistance pattern from a lightweight cable-driven ankle exoskeleton reduced the metabolic cost of walking by 17.1% and decreased soleus muscle activity by 40.9%, indicating significant improvements in walking efficiency.

The study identified an effective initial assistance pattern with 48% peak torque timing and 0.75 N·m·kg-1 peak torque magnitude, which can guide future optimization processes for enhancing exoskeleton performance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Improving Walking Economy With an Ankle Exoskeleton Prior to Human-in-the-Loop Optimization. Wang, W., Chen, J., Ding, J., et al.[2022]

Exoskeletons have advanced significantly over the past two decades, showing promise in enhancing movement for both unimpaired users and those with gait impairments, indicating their potential for rehabilitation and mobility assistance.

The review emphasizes the need for further research to address clinical requirements and challenges in exoskeleton technology, suggesting that while progress has been made, there are still important areas to explore for effective gait rehabilitation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Opportunities and challenges in the development of exoskeletons for locomotor assistance. Siviy, C., Baker, LM., Quinlivan, BT., et al.[2023]

A review of 69 clinical trials involving various pathologies showed that about 50% of participants had spinal cord injuries, highlighting the significant use of exoskeletons in this area of rehabilitation.

The study suggests the development of a new modular exoskeleton with a distributed control system to enhance adaptability and effectiveness for different medical conditions, emphasizing the need for personalized therapies in rehabilitation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Wearable rehabilitation exoskeletons of the lower limb: analysis of versatility and adaptability. Plaza, A., Hernandez, M., Puyuelo, G., et al.[2023]

The Vacoped® dynamic vacuum ankle orthosis significantly reduces peak plantar pressure during full weight bearing, with reductions to 68% for the hindfoot and 60% for the forefoot compared to normal gait, indicating its efficacy in off-loading pressure on the foot.

When limiting weight bearing to 10% of body weight, the orthosis further decreased plantar pressure to as low as 19% for the hindfoot, but the integrated physical strain trainer was not effective in accurately monitoring this level of restriction for the entire foot.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Foot loading with an ankle-foot orthosis: the accuracy of an integrated physical strain trainer. Pauser, J., Jendrissek, A., Brem, M., et al.[2021]

A survey conducted among exoskeleton users highlighted the need for a rigorous risk assessment process to ensure the safety and effectiveness of exoskeleton technology, which is rapidly growing in various applications.

Key safety concerns identified include misalignments and unintended device motion, which could significantly impact user safety and should be addressed in future risk assessments and mitigation strategies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Relevance of hazards in exoskeleton applications: a survey-based enquiry. Massardi, S., Pinto-Fernandez, D., Babič, J., et al.[2023]

The study developed a fall control strategy for powered lower limb exoskeletons (LLEs) that significantly reduces the risk of head injuries and decreases hip impact velocity by over 50% during simulated falls.

By optimizing joint trajectories and torque profiles, the new strategy allows for safer independent use of LLEs, addressing a major safety concern that currently limits their use to supervised settings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Developing safe fall strategies for lower limb exoskeletons. Khalili, M., Borisoff, JF., Van der Loos, HFM.[2018]

A systematic review of 50 studies involving 985 subjects revealed that adverse events (AEs) occurred in 18 studies, with over 169 device-related AEs reported, primarily soft tissue injuries and musculoskeletal issues, particularly in end-effector and exoskeleton devices.

The most common risks associated with stationary robot-assisted gait training include excessive pressure and shear at the interface between the device and the user, as well as misalignments that increase forces on the musculoskeletal system, highlighting the need for improved reporting and safety measures.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Occurrence and Type of Adverse Events During the Use of Stationary Gait Robots-A Systematic Literature Review. Bessler, J., Prange-Lasonder, GB., Schulte, RV., et al.[2021]

A portable ankle exoskeleton was optimized for real-world use, showing that it can enhance walking speed by 9% and improve energy efficiency by reducing energy consumption by 17% compared to normal shoes.

The optimization process was significantly faster in real-world conditions, identifying effective assistance parameters four times quicker than traditional laboratory methods, demonstrating the potential for personalized exoskeleton assistance in everyday settings.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Personalizing exoskeleton assistance while walking in the real world. Slade, P., Kochenderfer, MJ., Delp, SL., et al.[2022]

Powered exoskeletons, like the ReWalk™, Indego™, and Ekso™, have been approved as medical devices to help individuals with gait disabilities walk upright, but the understanding of their risks and safety is still developing.

There is a significant need for standardized regulations and awareness of potential risks associated with powered exoskeletons to ensure safe and effective use, as current criteria for their use and reported adverse events vary widely.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Risk management and regulations for lower limb medical exoskeletons: a review. He, Y., Eguren, D., Luu, TP., et al.[2020]

Assistive exoskeletons using trajectory following control can create stable walking patterns, but they lack the ability for users to customize their gait preferences intuitively.

The study demonstrated that optimizing between natural walking and gait energy can enhance the customization of exoskeletons, leading to improved user experience and stability in bipedal gait through simulations in a virtual constraint framework.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Assistive Exoskeleton Control with User-Tuned Multi-Objective Optimization. Stewart, K., Diduch, C., Sensinger, J.[2020]

A new simulation model for transfemoral prostheses was developed, which included a muscle model for the residual limb, to optimize knee joint friction and reduce energy expenditure during walking.

The optimal knee joint friction calculated from the model closely matched the friction preferred by the subject during normal walking, suggesting that personalized adjustments can enhance walking efficiency for amputees.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Dynamic optimization of transfemoral prosthesis during swing phase with residual limb model. Suzuki, Y.[2022]

A study using a hip-knee-ankle exoskeleton emulator showed that optimizing whole-leg assistance significantly reduced the metabolic cost of walking on inclines by at least 50% compared to walking without assistance, indicating high efficacy for exoskeletons in real-world settings.

The research found that as the incline increased, the required torque and power from the exoskeleton also increased, suggesting that future designs should focus on providing greater power to enhance performance on steeper terrains.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: A Case Series. Franks, PW., Bryan, GM., Reyes, R., et al.[2022]

Citations

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

Human-in-the-loop optimization of exoskeleton assistance during walking. [2018]

2. Switzerland pubmed.ncbi.nlm.nih.gov

Improving Walking Economy With an Ankle Exoskeleton Prior to Human-in-the-Loop Optimization. [2022]

3. England pubmed.ncbi.nlm.nih.gov

Opportunities and challenges in the development of exoskeletons for locomotor assistance. [2023]

4. England pubmed.ncbi.nlm.nih.gov

Wearable rehabilitation exoskeletons of the lower limb: analysis of versatility and adaptability. [2023]

5. Germany pubmed.ncbi.nlm.nih.gov

Foot loading with an ankle-foot orthosis: the accuracy of an integrated physical strain trainer. [2021]

6. England pubmed.ncbi.nlm.nih.gov

Relevance of hazards in exoskeleton applications: a survey-based enquiry. [2023]

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

Developing safe fall strategies for lower limb exoskeletons. [2018]

8. Switzerland pubmed.ncbi.nlm.nih.gov

Occurrence and Type of Adverse Events During the Use of Stationary Gait Robots-A Systematic Literature Review. [2021]

9. England pubmed.ncbi.nlm.nih.gov

Personalizing exoskeleton assistance while walking in the real world. [2022]

10. New Zealand pubmed.ncbi.nlm.nih.gov

Risk management and regulations for lower limb medical exoskeletons: a review. [2020]

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

Assistive Exoskeleton Control with User-Tuned Multi-Objective Optimization. [2020]

12. France pubmed.ncbi.nlm.nih.gov

Dynamic optimization of transfemoral prosthesis during swing phase with residual limb model. [2022]

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

The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: A Case Series. [2022]