Exoskeleton Optimization for Peripheral Artery Disease
Recruiting in Palo Alto (17 mi)
Age: 18+
Sex: Any
Travel: May Be Covered
Time Reimbursement: Varies
Trial Phase: Academic
Recruiting
Sponsor: University of Nebraska
Disqualifiers: Neurological, Musculoskeletal, Cardiovascular, Pulmonary, others
No Placebo Group
Trial Summary
What is the purpose of this trial?The investigators will evaluate a potentially faster and more clinically feasible method to optimize exoskeletons in pilot tests in healthy in preparation for patients with peripheral artery disease.
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 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.
12345Is 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.
678910How 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.
12111213Eligibility Criteria
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.
+3 more
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.
+5 more
Trial Timeline
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
Participant Groups
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.
2Treatment groups
Experimental Treatment
Group I: Optimal assistance patternExperimental Treatment1 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: Effects on enduranceExperimental Treatment1 Intervention
Determine effects on endurance of participants using ground reaction force (Bertec treadmill), walking speed (Bertec treadmill), indirect calorimetry (Cosmed), and motion capture (Vicon).
Find a Clinic Near You
Research Locations NearbySelect from list below to view details:
University of Nebraska OmahaOmaha, NE
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Who Is Running the Clinical Trial?
University of NebraskaLead Sponsor
References
Human-in-the-loop optimization of exoskeleton assistance during walking. [2018]Exoskeletons and active prostheses promise to enhance human mobility, but few have succeeded. Optimizing device characteristics on the basis of measured human performance could lead to improved designs. We have developed a method for identifying the exoskeleton assistance that minimizes human energy cost during walking. Optimized torque patterns from an exoskeleton worn on one ankle reduced metabolic energy consumption by 24.2 ± 7.4% compared to no torque. The approach was effective with exoskeletons worn on one or both ankles, during a variety of walking conditions, during running, and when optimizing muscle activity. Finding a good generic assistance pattern, customizing it to individual needs, and helping users learn to take advantage of the device all contributed to improved economy. Optimization methods with these features can substantially improve performance.
Improving Walking Economy With an Ankle Exoskeleton Prior to Human-in-the-Loop Optimization. [2022]Lower limb robotic exoskeletons have shown the capability to enhance human locomotion for healthy individuals or to assist motion rehabilitation and daily activities for patients. Recent advances in human-in-the-loop optimization that allowed for assistance customization have demonstrated great potential for performance improvement of exoskeletons. In the optimization process, subjects need to experience multiple types of assistance patterns, thus, leading to a long evaluation time. Besides, some patterns may be uncomfortable for the wearers, thereby resulting in unpleasant optimization experiences and inaccurate outcomes. In this study, we investigated the effectiveness of a series of ankle exoskeleton assistance patterns on improving walking economy prior to optimization. We conducted experiments to systematically evaluate the wearers' biomechanical and physiological responses to different assistance patterns on a lightweight cable-driven ankle exoskeleton during walking. We designed nine patterns in the optimization parameters range which varied peak torque magnitude and peak torque timing independently. Results showed that metabolic cost of walking was reduced by 17.1 ± 7.6% under one assistance pattern. Meanwhile, soleus (SOL) muscle activity was reduced by 40.9 ± 19.8% with that pattern. Exoskeleton assistance changed maximum ankle dorsiflexion and plantarflexion angle and reduced biological ankle moment. Assistance pattern with 48% peak torque timing and 0.75 N·m·kg -1 peak torque magnitude was effective in improving walking economy and can be selected as an initial pattern in the optimization procedure. Our results provided a preliminary understanding of how humans respond to different assistances and can be used to guide the initial assistance pattern selection in the optimization.
Opportunities and challenges in the development of exoskeletons for locomotor assistance. [2023]Exoskeletons can augment the performance of unimpaired users and restore movement in individuals with gait impairments. Knowledge of how users interact with wearable devices and of the physiology of locomotion have informed the design of rigid and soft exoskeletons that can specifically target a single joint or a single activity. In this Review, we highlight the main advances of the past two decades in exoskeleton technology and in the development of lower-extremity exoskeletons for locomotor assistance, discuss research needs for such wearable robots and the clinical requirements for exoskeleton-assisted gait rehabilitation, and outline the main clinical challenges and opportunities for exoskeleton technology.
Wearable rehabilitation exoskeletons of the lower limb: analysis of versatility and adaptability. [2023]To analyse the versatility and adaptability of commercially available exoskeletons for mobility assistance and their adaptation to diverse pathologies through a review of clinical trials in robotic lower limb training.
Foot loading with an ankle-foot orthosis: the accuracy of an integrated physical strain trainer. [2021]To investigate the value of a built-in physical strain trainer for the monitoring of partial weight bearing with an ankle-foot orthosis.
Relevance of hazards in exoskeleton applications: a survey-based enquiry. [2023]Exoskeletons are becoming the reference technology for assistance and augmentation of human motor functions in a wide range of application domains. Unfortunately, the exponential growth of this sector has not been accompanied by a rigorous risk assessment (RA) process, which is necessary to identify the major aspects concerning the safety and impact of this new technology on humans. This situation may seriously hamper the market uptake of new products. This paper presents the results of a survey that was circulated to understand how hazards are considered by exoskeleton users, from research and industry perspectives. Our analysis aimed to identify the perceived occurrence and the impact of a sample of generic hazards, as well as to collect suggestions and general opinions from the respondents that can serve as a reference for more targeted RA. Our results identified a list of relevant hazards for exoskeletons. Among them, misalignments and unintended device motion were perceived as key aspects for exoskeletons' safety. This survey aims to represent a first attempt in recording overall feedback from the community and contribute to future RAs and the identification of better mitigation strategies in the field.
Developing safe fall strategies for lower limb exoskeletons. [2018]One of the main challenges in the use of a powered lower limb exoskeleton (LLE) is to ensure that balance is maintained throughout the operation of the device. Since no control strategy has yet been implemented that prevents falls in the case of a loss of balance, head or other serious injuries may occur during independent use of LLEs in the event of a fall. These safety concerns limit LLEs in the community to supervised use only. Using the backward fall as a model, we used optimization techniques to develop safe fall control strategies in order to avoid head impact and mitigate the impact velocity of the hips. From available human biomechanics data, we first developed an optimization methodology to study falls of healthy people. The results showed similar kinematic and dynamic characteristics to findings of previous studies on real-life human falls. Second, we extended the optimization methodology to include characteristics of a hypothetical LLE and to generate optimal joint trajectories and optimal torque profiles for the fall duration. The results revealed that by applying the optimal fall strategy, the severity of a simulated fall was minimized compared to when the device fell with locked joints (i.e., how currently used exoskeletons fall): head impact was avoided and hip impact velocity was reduced by more than 50%.
Occurrence and Type of Adverse Events During the Use of Stationary Gait Robots-A Systematic Literature Review. [2021]Robot-assisted gait training (RAGT) devices are used in rehabilitation to improve patients' walking function. While there are some reports on the adverse events (AEs) and associated risks in overground exoskeletons, the risks of stationary gait trainers cannot be accurately assessed. We therefore aimed to collect information on AEs occurring during the use of stationary gait robots and identify associated risks, as well as gaps and needs, for safe use of these devices. We searched both bibliographic and full-text literature databases for peer-reviewed articles describing the outcomes of stationary RAGT and specifically mentioning AEs. We then compiled information on the occurrence and types of AEs and on the quality of AE reporting. Based on this, we analyzed the risks of RAGT in stationary gait robots. We included 50 studies involving 985 subjects and found reports of AEs in 18 of those studies. Many of the AE reports were incomplete or did not include sufficient detail on different aspects, such as severity or patient characteristics, which hinders the precise counts of AE-related information. Over 169 device-related AEs experienced by between 79 and 124 patients were reported. Soft tissue-related AEs occurred most frequently and were mostly reported in end-effector-type devices. Musculoskeletal AEs had the second highest prevalence and occurred mainly in exoskeleton-type devices. We further identified physiological AEs including blood pressure changes that occurred in both exoskeleton-type and end-effector-type devices. Training in stationary gait robots can cause injuries or discomfort to the skin, underlying tissue, and musculoskeletal system, as well as unwanted blood pressure changes. The underlying risks for the most prevalent injury types include excessive pressure and shear at the interface between robot and human (cuffs/harness), as well as increased moments and forces applied to the musculoskeletal system likely caused by misalignments (between joint axes of robot and human). There is a need for more structured and complete recording and dissemination of AEs related to robotic gait training to increase knowledge on risks. With this information, appropriate mitigation strategies can and should be developed and implemented in RAGT devices to increase their safety.
Personalizing exoskeleton assistance while walking in the real world. [2022]Personalized exoskeleton assistance provides users with the largest improvements in walking speed1 and energy economy2-4 but requires lengthy tests under unnatural laboratory conditions. Here we show that exoskeleton optimization can be performed rapidly and under real-world conditions. We designed a portable ankle exoskeleton based on insights from tests with a versatile laboratory testbed. We developed a data-driven method for optimizing exoskeleton assistance outdoors using wearable sensors and found that it was equally effective as laboratory methods, but identified optimal parameters four times faster. We performed real-world optimization using data collected during many short bouts of walking at varying speeds. Assistance optimized during one hour of naturalistic walking in a public setting increased self-selected speed by 9 ± 4% and reduced the energy used to travel a given distance by 17 ± 5% compared with normal shoes. This assistance reduced metabolic energy consumption by 23 ± 8% when participants walked on a treadmill at a standard speed of 1.5 m s-1. Human movements encode information that can be used to personalize assistive devices and enhance performance.
Risk management and regulations for lower limb medical exoskeletons: a review. [2020]Gait disability is a major health care problem worldwide. Powered exoskeletons have recently emerged as devices that can enable users with gait disabilities to ambulate in an upright posture, and potentially bring other clinical benefits. In 2014, the US Food and Drug Administration approved marketing of the ReWalk™ Personal Exoskeleton as a class II medical device with special controls. Since then, Indego™ and Ekso™ have also received regulatory approval. With similar trends worldwide, this industry is likely to grow rapidly. On the other hand, the regulatory science of powered exoskeletons is still developing. The type and extent of probable risks of these devices are yet to be understood, and industry standards are yet to be developed. To address this gap, Manufacturer and User Facility Device Experience, Clinicaltrials.gov, and PubMed databases were searched for reports of adverse events and inclusion and exclusion criteria involving the use of lower limb powered exoskeletons. Current inclusion and exclusion criteria, which can determine probable risks, were found to be diverse. Reported adverse events and identified risks of current devices are also wide-ranging. In light of these findings, current regulations, standards, and regulatory procedures for medical device applications in the USA, Europe, and Japan were also compared. There is a need to raise awareness of probable risks associated with the use of powered exoskeletons and to develop adequate countermeasures, standards, and regulations for these human-machine systems. With appropriate risk mitigation strategies, adequate standards, comprehensive reporting of adverse events, and regulatory oversight, powered exoskeletons may one day allow individuals with gait disabilities to safely and independently ambulate.
Assistive Exoskeleton Control with User-Tuned Multi-Objective Optimization. [2020]Assistive exoskeletons that utilize trajectory following control have been shown to produce stable gait for users. These however, do not allow intuitive tuning to customize gait to users' preferences. When persons walk on their own, they balance a variety of needs such as speed, comfort, and energy. Providing user tuning by optimizing between different gait performance measures gives an intuitive flexibility. We have shown the optimization between natural walking and gait energy produces stable bipedal gait through simulation in a virtual constraint framework. This verification shows validity of the methodology and framework for improving tuning and customization of assistive exoskeletons.
Dynamic optimization of transfemoral prosthesis during swing phase with residual limb model. [2022]A new simulation model was created with a transfemoral prosthesis including a residual limb muscle model during the swing phase. The optimal knee joint friction value was calculated to minimize muscle metabolic energy expenditure. Using this model to examine how an amputee could walk as fast as possible, the minimum swing duration was calculated. The obtained optimal joint friction value was close to the value the subject preferred when walking normally. The calculated minimum swing duration was close to the time the subject could achieve. The method of dynamic optimization with a musculoskeletal model used in this study indicated the possibility of obtaining optimal mechanical properties suited to each amputee's capability of mastering control of his/her residual limb.
The Effects of Incline Level on Optimized Lower-Limb Exoskeleton Assistance: A Case Series. [2022]For exoskeletons to be successful in real-world settings, they will need to be effective across a variety of terrains, including on inclines. While some single-joint exoskeletons have assisted incline walking, recent successes in level-ground assistance suggest that greater improvements may be possible by optimizing assistance of the whole leg. To understand how exoskeleton assistance should change with incline, we used human-in-the-loop optimization to find whole-leg exoskeleton assistance torques that minimized metabolic cost on a range of grades. We optimized assistance for three non-disabled, expert participants on 5 degree, 10 degree, and 15 degree inclines using a hip-knee-ankle exoskeleton emulator. For all assisted conditions, the cost of transport was reduced by at least 50% relative to walking in the device with no assistance, which is a large improvement to walking comparable to the benefits of whole-leg assistance on level-ground (N = 3). Optimized extension torque magnitudes and exoskeleton power increased with incline. Hip extension, knee extension and ankle plantarflexion often grew as large as allowed by comfort-based limits. Applied powers on steep inclines were double the powers applied during level-ground walking, indicating that greater exoskeleton power may be optimal in scenarios where biological powers and costs are higher. Future exoskeleton devices could deliver large improvements in walking performance across a range of inclines if they have sufficient torque and power capabilities.