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

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to improve walking assistance for people with peripheral artery disease (PAD) using wearable exoskeletons. Researchers will test new methods to enhance these devices by adjusting their assistance patterns and evaluating endurance. The goal is to make the exoskeletons more effective for those who struggle to walk long distances due to PAD. Individuals with a history of leg pain when walking and who can walk on a treadmill for short periods might be suitable candidates for this study. As an unphased trial, this study offers a unique opportunity to contribute to innovative research that could enhance mobility for PAD patients.

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.

What prior data suggests that these exoskeletal devices are safe for patients with peripheral artery disease?

Research has shown that wearable exoskeletons are generally safe for use. Studies have found that these devices can improve muscle strength, balance, and walking ability in individuals with various conditions, including nerve injuries. Most users tolerate them well, and no major negative effects have been reported.

For the specific treatment being studied, which uses exoskeletons for people with peripheral artery disease, existing trials have not identified any safety concerns. Similar studies have found the exoskeletons to be safe, with no major differences in results compared to other assistive devices.

Overall, evidence suggests that exoskeletons, when used to improve mobility, are safe and well-tolerated. Participants in trials with these devices generally do not experience serious side effects, making them a promising option for enhancing mobility in clinical settings. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about this trial because it explores innovative ways to optimize exoskeleton use for people with Peripheral Artery Disease (PAD). Unlike current treatments that primarily focus on medications and lifestyle changes to improve blood flow, this trial investigates how personalized exoskeleton adjustments might enhance walking efficiency and endurance. By using an optimization algorithm to tailor the assistance pattern of the hip exoskeleton, the trial aims to minimize gait variability, potentially leading to more effective mobility support. Additionally, the trial evaluates endurance through advanced measurements like ground reaction force and motion capture, offering a comprehensive approach to understanding how exoskeletons can better aid individuals with PAD.

What evidence suggests that this exoskeleton optimization is effective for peripheral artery disease?

Research shows that wearable exoskeletons can improve walking and strengthen muscles. Studies have found that these devices assist individuals with neurological injuries by enhancing balance and gait. They are generally safe and effective, particularly for rehabilitation. Early findings suggest a significant impact on muscle use and fatigue, which can benefit people with peripheral artery disease (PAD). This trial will explore two approaches: the "Optimal Assistance Pattern," which uses an optimization algorithm to adjust hip exoskeleton assistance during walking, and the "Endurance Effects," which evaluates endurance using various metrics. Although exoskeletons continue to undergo improvements, these early results are promising for enhancing mobility in people with PAD. ^{4 5 6 7 8}

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

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]

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]

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 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]

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 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]

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 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]

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]

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]

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