An overview and categorization of dynamic arm supports for people with decreased arm function

Use of a dynamic arm support to drive a power wheelchair: a case report

PURPOSE

Dynamic arm supports (DAS) can assist individuals with severe upper limb disabilities who use a wheelchair to accomplish their daily activities. The objective of this case series was to assess the potential of a DAS to improve power wheelchair (PWC) control in real-life contexts and to describe the integration process. A secondary objective was to explore factors that may influence the DAS integration process.

METHODS

This case series includes four participants fitted with the Kinova DAS O110. A one-year follow-up was planned for each participant with qualitative and quantitative data collection to assess DAS outcomes. Assessment methods were selected to cover the three vantages of assistive technology outcomes assessment: effectiveness, subjective well-being, and social significance.

RESULTS

Among the four participants, one used the DAS to help with his wheelchair control for at least 12 months (successful integration). For him, the DAS led to significantly improved wheelchair skills and an important positive psychosocial impact. He was, however, only able to use the DAS for PWC control (no effects on other daily activities), and could not use it in some contexts because the device increased his PWC width. As for the other participants, they stopped using the DAS for different reasons, including a DAS-related adverse event.

CONCLUSION

This study demonstrated that a wheelchair-bound DAS has the potential to improve PWC use, but successful integration requires specific factors. The service delivery process and the environmental accessibility are crucial for the successful integration of such a device and to avoid safety issues.IMPLICATIONS FOR REHABILITATIONNo study deeply assessed the impacts of dynamic arm support on power wheelchair control, and the associated facilitators and obstacles.A wheelchair-bound dynamic arm support has the potential to improve power wheelchair control for individuals with upper limb disabilities and to lead to positive psychosocial impacts if some conditions conductive to successful integration are met.The service delivery process and the environmental accessibility appear as crucial aspects for the successful integration of a new device, such as dynamic arm support and avoiding safety issues.

Model-Based Upper-Limb Gravity Compensation Strategies for Active Dynamic Arm Supports

NeuroMuscular Disorders (NMDs) may induce difficulties to perform daily life activities in autonomy. For people with NMDs affecting the upper-limb mobility, Dynamic Arm Supports (DASs) turn out to be relevant assistive devices. In particular, active DASs benefit from an external power source to support severely impaired people. However, commercially available active devices are controlled with push buttons, which add cognitive load and discomfort. To alleviate this issue, we propose a new force-based assistive control framework. In this preliminary work, we focus on the computation of a feedforward force to compensate upper-limb gravity. Four strategies based on a biomechanical model of the upper limb, tuned using anthropometric measurements, are proposed and evaluated. The first one is based on the potential energy of the upper-limb, the second one makes a compromise between the shoulder and elbow torques, the third one minimizes the sum of the squared user joint torques and the last one uses a probabilistic approach to minimize the expected torque norm in the presence of model uncertainties. These strategies have been evaluated quantitatively through an experiment including nine participants with an active DAS prototype. The activity of six muscles was measured and used to compute the Mean Effort Index (MEI) which represents the global effort required to maintain the pose. A statistical analysis shows that the four strategies significantly lower the MEI (p-value < 0.001).

The size and behavior of virtual objects have influence on functional exercise and motivation of persons with multiple sclerosis: a randomized study

The consequences of multiple sclerosis are problems with limb movement, coordination, and vision. Heretofore a combination of therapy and additional medications can alter the course of the disease and reduce upper extremity disability. We developed a virtual environment for pick-and-place tasks as a supportive tool to address the problem of challenging task in occupational therapy. The primary objective of the study was to investigate the influence of size and bounce on proximal and fine motor performance and intrinsic motivation. The secondary objective was to examine how the absence of challenge may decrease intrinsic motivation and heart rate. The randomized trial involved 84/107 eligible inpatients with multiple sclerosis. They were divided into 4 groups by computer randomization: Group 1 small and bouncing, Group 2 small and non-bouncing, Group 3 large and bouncing, and Group 4 large and non-bouncing virtual cubes. Each participant completed 50 sessions of up to 2 min each in approximately 14 days. Before commencement of the study the participants completed visuospatial and cognitive tests. Participants' subjective experiences were assessed daily using the intrinsic motivation inventory. Before and after the study, the box and block test and the 9-hole peg test were administered. Kinematic analysis showed significant differences between groups (average manipulation time p = 0.008, inserted cubes p = 0.004). Group 4 was the most successful (inserted cubes > 9) and the fastest (63.4 SD 25.8 s), but had low pressure/tension and heart rate. Group 1 was the slowest (88.9 SD 28.2 s) but had increased interest/enjoyment in the task under higher pressure/tension. There were substantial differences in intrinsic motivation between the 1st and last sessions within groups (Cohen's U3 < 0.3 or > 0.8). The size and behavior of virtual objects may be important for training proximal movements and fine motor skills in people with multiple sclerosis. Furthermore, the demonstrated approach proved to be effective and may reduce upper extremity disability in the long term if intrinsic motivation can be sustained longer with a challenging task.Trial registration The small scale randomized pilot trial has been registered at ClinicalTrials.gov Identifier: NCT04266444, 12/02/2020, https://clinicaltrials.gov/ct2/show/NCT04266444 .

User Based Development and Test of the EXOTIC Exoskeleton: Empowering Individuals with Tetraplegia Using a Compact, Versatile, 5-DoF Upper Limb Exoskeleton Controlled through Intelligent Semi-Automated Shared Tongue Control

This paper presents the EXOTIC- a novel assistive upper limb exoskeleton for individuals with complete functional tetraplegia that provides an unprecedented level of versatility and control. The current literature on exoskeletons mainly focuses on the basic technical aspects of exoskeleton design and control while the context in which these exoskeletons should function is less or not prioritized even though it poses important technical requirements. We considered all sources of design requirements, from the basic technical functions to the real-world practical application. The EXOTIC features: (1) a compact, safe, wheelchair-mountable, easy to don and doff exoskeleton capable of facilitating multiple highly desired activities of daily living for individuals with tetraplegia; (2) a semi-automated computer vision guidance system that can be enabled by the user when relevant; (3) a tongue control interface allowing for full, volitional, and continuous control over all possible motions of the exoskeleton. The EXOTIC was tested on ten able-bodied individuals and three users with tetraplegia caused by spinal cord injury. During the tests the EXOTIC succeeded in fully assisting tasks such as drinking and picking up snacks, even for users with complete functional tetraplegia and the need for a ventilator. The users confirmed the usability of the EXOTIC.

A force-based human machine interface to drive a motorized upper limb exoskeleton. a pilot study

Muscular dystrophy is a strongly invalidating disease that causes the progressive loss of motor skills. The use of assistive devices, especially those in support of the upper limb, can increase the ability to perform daily-life activities and foster a partial recovery of the lost motor functionalities. However, for the use of these devices to be truly effective and accepted by patients, their activation must coincide with the user's intention to move. This work describes a new human-machine interface based on the integration of a six-axis force sensor to drive an upper limb motorized exoskeleton. This novel system can detect the patient's intention to move and produce displacements of the robotic device that are of magnitude and direction consistent with the user's wishes. The integration of the force-sensor interface in the BRIDGE/EMPATIA exoskeletal system was successful, and tests performed on both healthy and dystrophic subjects showed promising results, especially for the execution of planar movements.

Controlling an effector with eye movements: The effect of entangled sensory and motor responsibilities

Restoring arm and hand function has been indicated by individuals with tetraplegia as one of the most important factors for regaining independence. The overall goal of our research is to develop assistive technologies that allow individuals with tetraplegia to control functional reaching movements. This study served as an initial step toward our overall goal by assessing the feasibility of using eye movements to control the motion of an effector in an experimental environment. We aimed to understand how additional motor requirements placed on the eyes affected eye-hand coordination during functional reaching. We were particularly interested in how eye fixation error was affected when the sensory and motor functions of the eyes were entangled due to the additional motor responsibility. We recorded participants’ eye and hand movements while they reached for targets on a monitor. We presented a cursor at the participant’s point of gaze position which can be thought of as being similar to the control of an assistive robot arm. To measure eye fixation error, we used an offline filter to extract eye fixations from the raw eye movement data. We compared the fixations to the locations of the targets presented on the monitor. The results show that not only are humans able to use eye movements to direct the cursor to a desired location (1.04 ± 0.15 cm), but they can do so with error similar to that of the hand (0.84 ± 0.05 cm). In other words, despite the additional motor responsibility placed on the eyes during direct eye-movement control of an effector, the ability to coordinate functional reaching movements was unaffected. The outcomes of this study support the efficacy of using the eyes as a direct command input for controlling movement.

Evaluation of the usability of an actively actuated arm support

Dynamic arm supports can be used to increase the autonomy of people with upper limb disabilities, but their usability is often poorly documented. The objective of this study is to evaluate the usability of an actuated arm support (AAS), namely the Gowing power-assisted arm support. Nine participants with neurological disorders restricting their upper limb capacities (DASH = 63.51 ± 7.72) completed various tasks (Upper Extremity Performance Test for the Elderly (TEMPA)) with and without the AAS. Users' satisfaction (Quebec User Evaluation of Satisfaction with assistive Technology (QUEST)) and perceived benefits of the device (semi-structured interviews) were assessed. Large (effect size ≥ 1.15) and statistically significant (p < .05) improvements were found in the TEMPA functional rating, range of motion, strength, precision of gross movements and prehension patterns subscales while using the AAS. Two third of the participants were quite or very satisfied with the arm support (QUEST > 4/5) and interviews were positive about its usefulness in daily living activities. Our study demonstrated that the use of an AAS could result in significant improvements in the autonomy of people with upper limb disabilities.

Wheelchair-Mounted Upper Limb Robotic Exoskeleton with Adaptive Controller for Activities of Daily Living

Neuro-muscular disorders and diseases such as cerebral palsy and Duchenne Muscular Dystrophy can severely limit a person's ability to perform activities of daily living (ADL). Exoskeletons can provide an active or passive support solution to assist these groups of people to perform ADL. This study presents an artificial neural network-trained adaptive controller mechanism that uses surface electromyography (sEMG) signals from the human forearm to detect hand gestures and navigate an in-house-built wheelchair-mounted upper limb robotic exoskeleton based on the user's intent while ensuring safety. To achieve the desired position of the exoskeleton based on human intent, 10 hand gestures were recorded from 8 participants without upper limb movement disabilities. Participants were tasked to perform water bottle pick and place activities while using the exoskeleton, and sEMG signals were collected from the forearm and processed through root mean square, median filter, and mean feature extractors prior to training a scaled conjugate gradient backpropagation artificial neural network. The trained network achieved an average of more than 93% accuracy, while all 8 participants who did not have any prior experience of using an exoskeleton were successfully able to perform the task in less than 20 s using the proposed artificial neural network-trained adaptive controller mechanism. These results are significant and promising thus could be tested on people with muscular dystrophy and neuro-degenerative diseases.

Feasibility and effectiveness of a novel dynamic arm support in persons with spinal muscular atrophy and duchenne muscular dystrophy

Background

Neuromuscular disorders (NMD) commonly affect the upper extremity. Due to muscle weakness, performance of daily activities becomes increasingly difficult, which leads to reduced independence and quality of life. In order to support the performance of upper extremity tasks, dynamic arm supports may be used. The Yumen Arm is a novel dynamic arm support specially developed for people with NMD. The aim of this study is to evaluate the feasibility and effectiveness of the Yumen Arm in persons with Duchenne Muscular Dystrophy (DMD) and persons with Spinal Muscular Atrophy (SMA).

Methods

Three persons with DMD and three persons with SMA participated in this study. All participants conducted a set of measures with and without the Yumen Arm. Outcome measures were: active range of motion of the arm and trunk (i.e. Reachable Workspace, Functional Workspace, and trunk movement), fatigue (OMNI-RPE), Performance of Upper Limb (PUL) scale and some additional activities of daily living. User experiences were collected using a questionnaire.

Results

The Yumen Arm could be used by all participants. Results showed a median increase in active range of motion (4% relative surface area), and a median increase of function ability (>11% PUL score) when using the Yumen Arm. In addition, three out of four (data from 2 participants was missing) participants indicated that activity performance was less fatiguing when using the Yumen Arm. Four out of five (data from 1 participant was missing) participants indicated that they would like to use the Yumen Arm in their daily lives.

Conclusion

This study is one of the first studies describing a range of objective measures to examine the effectiveness of a dynamic arm support. Based on these measurements we can conclude that the Yumen Arm effectively improves arm function in NMD patients, however the effectiveness varies a lot between individual subjects. We provided detailed recommendations for the improvement of the Yumen Arm, and possible also for the development of other dynamic arm supports. This study showed a lot of variability between individual subjects, which emphasizes the importance of tuning dynamic arm supports based on individual user characteristics, such as scoliosis, functional capacity and muscle strength.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12984-021-00868-6.

Recommendations for studies on dynamic arm support devices in people with neuromuscular disorders: a scoping review with expert-based discussion

PURPOSE

Neuromuscular disorders are characterised by muscle weakness that limits upper extremity mobility, but can be alleviated with dynamic arm support devices. Current research highlights the importance and difficulties of evidence-based recommendations for device development. We aim to provide research recommendations primarily concerning upper extremity body functions, and secondarily activity and participation, environmental and personal factors.

METHODS

Evidence was synthesised from literature, ongoing studies, and expert opinions and tabulated within a framework based on a combination of the International Classification of Functioning, Disability and Health (ICF) model and contextual constructs.

RESULTS

Current literature mostly investigated the motor capacity of muscle function, joint mobility, and upper body functionality, and a few studies also addressed the impact on activity and participation. In addition, experts considered knowledge on device utilisation in the daily environment and characterising the beneficiaries better as important. Knowledge gaps showed that ICF model components and contextual constructs should be better integrated and more actively included in future research.

CONCLUSIONS

It is recommended to, first, integrate multiple ICF model components and contextual constructs within one study design. Second, include the influence of environmental and personal factors when developing and deploying a device. Third, include short-term and long-term measurements to monitor adaptations over time. Finally, include user satisfaction as guidance to evaluate the device effectiveness.IMPLICATIONS ON REHABILITATIONSynthesized evidence will support future research and development of dynamic arm supports.Tabulated evidence stresses the importance of integrating ICF model components and contextual constructs to fill the knowledge gaps.Presented knowledge gaps and proposed steps guide the set up of future studies on dynamic arm supports.

Daily Life Benefits and Usage Characteristics of Dynamic Arm Supports in Subjects with Neuromuscular Disorders

Neuromuscular disorders cause progressive muscular weakness, which limits upper extremity mobility and performance during activities of daily life. Dynamic arm supports can improve mobility and quality of life. However, their use is often discontinued over time for unclear reasons. This study aimed to evaluate whether users of dynamic arm supports demonstrate and perceive quantifiable mobility benefits over a period of two months. Nine users of dynamic arm supports were included in this observational study. They had different neuromuscular disorders and collectively used four different arm supports. They were observed for three consecutive weeks during which they were equipped with a multi-sensor network of accelerometers to assess the actual use of the arm support and they were asked to provide self-reports on the perceived benefits of the devices. Benefits were experienced mainly during anti-gravity activities and the measured use did not change over time. The self-reports provided contextual information in domains such as participation to social life, in addition to the sensor system. However self-reports overestimated the actual use by up to three-fold compared to the accelerometer measures. A combination of objective and subjective methods is recommended for meaningful and quantifiable mobility benefits during activities of daily life.

Upper-limb actuated exoskeleton for muscular dystrophy patients: preliminary results

Being able to perform a lost movement is an important experience towards increased independence and self-esteem, particularly for neuromuscular patients, who see their muscles weaken day after day. In this pilot study, preliminary results on the testing of a motorized upper-limb exoskeleton for muscular dystrophy patients are presented. The mechatronic system is a five Degrees of Freedom exoskeleton, which acts at shoulder, elbow, and wrist levels. It is designed to help severely impaired people to regain independence during daily-life activities. While wearing the exoskeleton, the user has the direct control of the system by actively piloting the position of end-effector by means of joystick or vocal control. The usability of the system and a quantitative assessment of arm functionality with and without the exoskeleton are evaluated on five muscular dystrophy patients. According to the objective functional benefit evaluation performed through the PUL scale, all participants strongly increased their range of motion and they were able to perform activities that were not possible without the exoskeleton, such as such as feeding, playing activities at the table, combing hair or using a keyboard. As for the evaluation of self-perceived functional benefit, four patients reflected the effective measured functional improvement. System usability has been evaluated to be good.

Mobile arm supports in Duchenne muscular dystrophy: a pilot study of user experience and outcomes

PURPOSE

This pilot study examined whether two different types of non-powered mobile arm supports (MAS) enhanced upper limb function and independence with activities of daily living (ADLs) in people with Duchenne muscular dystrophy (DMD).

METHOD

A mixed methods cross-sectional design was used. Participants were four males with DMD, aged 16 to 20 years (M = 18.25 years). Two participants were current MAS users, and two had previously used MAS. To explore experiences of MAS use, semi-structured interviews were undertaken, then transcribed verbatim and analysed thematically. To measure the impact of MAS on arm function and ADLs, participants using MAS completed the Performance of the Upper Limb (PUL) and the DMD Upper Limb Patient Reported Outcome Measure with and without MAS. Participants no longer using MAS only completed the PUL without MAS.

RESULTS

MAS enhanced upper limb function and independence with ADLs in three of four participants. Eating and drinking was most often positively impacted by MAS. Access to informal support for MAS set-up, and ongoing input from a clinician or assistive technology (AT) supplier with MAS expertise, were important enablers to successful MAS use. Barriers to use included inadequate upper limb strength, interference of MAS with wheelchair controls, and AT funding delays.

CONCLUSION

MAS should be considered by individuals with DMD and clinicians working with them as the disease progresses and strength declines. Potential barriers to MAS use need to be addressed to ensure maximum utility. AT funding delays must also be minimized to avoid impact on outcomes of people with DMD.Implications for RehabilitationIndividuals with DMD, and clinicians working with them, may consider MAS to aid achievement of functional goals as the disease progresses and upper limb function declines.Both objective and subjective outcome measures should be used when evaluating the effectiveness of MAS.Consideration should be given to the potential interference of MAS with wheelchair controls and the availability of informal or paid supports (e.g., family, support workers, teachers) to aid MAS use.Efficient and timely funding of MAS is required, as delays may negatively impact outcomes for people with progressive neurological conditions, such as DMD.

A Review on Design of Upper Limb Exoskeletons

Exoskeleton robotics has ushered in a new era of modern neuromuscular rehabilitation engineering and assistive technology research. The technology promises to improve the upper-limb functionalities required for performing activities of daily living. The exoskeleton technology is evolving quickly but still needs interdisciplinary research to solve technical challenges, e.g., kinematic compatibility and development of effective human–robot interaction. In this paper, the recent development in upper-limb exoskeletons is reviewed. The key challenges involved in the development of assistive exoskeletons are highlighted by comparing available solutions. This paper provides a general classification, comparisons, and overview of the mechatronic designs of upper-limb exoskeletons. In addition, a brief overview of the control modalities for upper-limb exoskeletons is also presented in this paper. A discussion on the future directions of research is included.

The Effectiveness of Wearable Upper Limb Assistive Devices in Degenerative Neuromuscular Diseases: A Systematic Review and Meta-Analysis

Background: This systematic review summarizes the current evidence about the effectiveness of wearable assistive technologies for upper limbs support during activities of daily living for individuals with neuromuscular diseases. Methods: Fourteen studies have been included in the meta-analysis, involving 184 participants. All included studies compared patients ability to perform functional tasks with and without assistive devices. Results: An overall effect size of 1.06 (95% CI = 0.76-1.36, p < 0.00001) was obtained, demonstrating that upper limbs assistive devices significantly improve the performance in activities of daily living in people with neuromuscular diseases. A significant interaction between studies evaluating functional improvement with externally-assessed outcome measures or self-perceived outcome measures has been detected. In particular, the effect size of the sub-group considering self-perceived scales was 1.38 (95% CI = 1.08-1.68), while the effect size of the other group was 0.77 (95% CI = 0.41-1.11), meaning that patients' perceived functional gain is often higher than the functional gain detectable through clinical scales. Conclusion: Overall, the quality of the evidence ranged from low to moderate, due to low number of studies and participants, limitations in the selection of participants and in the blindness of outcome assessors, and risk of publication bias. Significance: A large magnitude effect and a clear dose-response gradient were found, therefore, a strong recommendation, in favor of the use of assistive devices could be suggested.

Elbow Flexion Assist Orthosis for Arthrogryposis

INTRODUCTION

People with arthrogryposis multiplex congenita (AMC) often have muscle weakness in the biceps that makes elbow flexion difficult. An elbow-flexion assist orthosis was designed using the force of springs, combined with a sliding joint, to apply appropriate elbow torque to aid a user in lifting her hand to her mouth. The sliding joint allows an increasing elbow torque despite a decreasing spring force.

METHODS

The device was prototyped for a user with AMC. An occupational therapist measured the user's flexion with and without the device. Benchtop torque measurements were also determined and compared with user trials.

RESULTS

The assist orthosis applied an increasing torque as the elbow flexed, thereby allowing the subject to reach her mouth for feeding and then extend her elbow to a position of no applied torque. Without the device, the subject had active elbow flexion of 87 degrees. With the device, this flexion increased to 120 degrees.

CONCLUSION

The novel prototype is a lightweight, spring-powered flexion orthosis which can be made relatively easily and is potentially concealed under clothing. It provides the appropriate torque to move the hand against gravity and increases elbow-flexion of the user.

Modeling of Motorized Orthosis Control

Orthotic devices are defined as externally applied devices that are used to modify the structural and functional characteristics of the neuro-muscular and skeletal systems. The aim of the current study is to improve the control and movement of a robotic arm orthosis by means of an intelligent optimization system. Firstly, the control problem settlement is defined with the muscle, brain, and arm model. Subsequently, the optimization control, which based on a differential evolution algorithm, is developed to calculate the optimum gain values. Additionally, a cost function is defined in order to control and minimize the effort that is made by the subject and to assure that the algorithm follows as close as possible the defined setpoint value. The results show that, with the optimization algorithm, the necessary development force of the muscles is close to zero and the neural excitation level of biceps and triceps signal values are getting lower with a gain increase. Furthermore, the necessary development force of the biceps muscle to overcome a load added to the orthosis control system is practically the half of the one that is necessary without the optimization algorithm.

The perceived functional benefit of dynamic arm supports in daily life

Dynamic arm supports are provided to assist with activities of daily living (ADLs) in people with limited upper-limb function. However, the perceived functional benefit of these devices in daily life is unknown. Insight into the functional benefit may give direction to the development of new devices and may affect the factors that patients and their health care providers consider during the selection process of a device. A cross-sectional study involving 23 Dutch experienced dynamic arm support users was performed in the Netherlands. The study included a questionnaire, an interview, and an observation of ADL task performance in the domestic setting. Twenty participants completed this study. Five users had a large perceived functional benefit, nine a moderate benefit, and five no benefit (one was unable to indicate the benefit). People with limited functional abilities benefited most. Participants varied in the amount of device use, activities the device is used for, and reasons for using (or not using) the device. On an individual level, selection using a selection tool and a good evaluation of the prescription could improve user-device matches.

Quantitative measures with WREX usage

This paper presents the results of two surveys conducted with users of a functional upper extremity orthosis called the Wilmington Robotic EXoskeleton (WREX). The WREX is a passive anti-gravity arm orthosis that allows people with neuromuscular disabilities to move their arms in three dimensions. An online user survey with 55 patients was conducted to determine the benefits of the WREX. The survey asked 10 questions related to upper extremity function with and without the WREX as well as subjective impressions of the device. A second survey used a phone interview based on the Canadian Occupational Performance Measure (COPM). Parents rated their child's performance and satisfaction while partaking in important activities both with and without the exoskeleton device. Scores were assessed for change between the two conditions. Twenty-five families responded to this survey. Twenty-four out of 25 subjects reported greater levels of performance and satisfaction when they were wearing the WREX. The mean change in performance score was 3.61 points, and the mean change in satisfaction score was 4.44 points. Results show a statistically significant improvement in arm function for everyday tasks with the WREX.

Development and evaluation of a soft wearable weight support device for reducing muscle fatigue on shoulder

Compensating the weight of human limbs is important in reducing muscle fatigue experienced by manual laborers. In this study, a compact and lightweight soft wearable weight support device was developed and evaluated. The device supports gravitational force on the shoulder at any arm posture, although there are some limitations in its assistive performance. The device actuator consists of a cam-rod structure, a tendon-driven mechanism, and a rubber band. The desired assistive torque is translated to the shoulder joint along a tendon routing structure. Device performance was evaluated by measuring muscle activation in with-assist and without-assist conditions. Muscle activation on the deltoid was measured by surface electromyography. An experimental protocol consisting of a series of exercises was executed with six healthy subjects. The subjects raised and lowered their arm from 0 to 100 degrees for 30 times under eight conditions, which were combined with-assist and without-assist conditions, and holding the horizontal angle of the arm at 0, 30, 60, or 90 degrees against the sagittal plane. Surface electromyography data were pre-processed and analyzed using a root mean square method. When muscle fatigue occurs, the root mean square of the surface electromyography increases nonlinearly. This was calculated using the standard deviation of the root mean square. Three of six subjects showed decreased variation of the root mean square between the exercises in the with-assist condition. One subject’s result was significantly reduced (by about 57.6%) in the with-assist condition. In contrast, two subjects did not show significant difference between measurements taken in the with-assist and without-assist conditions. One subject was dropped from the experiment because the device did not fit the subject’s body. In conclusion, the effectiveness of the soft wearable weight support device in supporting shoulder movements was verified through the decreased variation of muscle activation.

User Evaluation of a Dynamic Arm Orthosis for People With Neuromuscular Disorders

This paper presents the results of an online survey conducted with users of a functional upper extremity orthosis called the Wilmington Robotic EXoskeleton (WREX). The WREX is a passive anti-gravity arm orthosis that allows people with neuromuscular disabilities to move their arms in three dimensions. The paper also describes the design of a novel lightweight 3-D printed WREX used for ambulatory children. Three different versions of the WREX are now offered to patients. Two can be mounted on a wheelchair and one to a body jacket for ambulatory patients. An online user survey with 55 patients was conducted to determine the benefits of the various WREXs. The survey asked ten questions related to upper extremity function with and without the WREX as well as subjective impressions of the device. Results show a statistically significant improvement in arm function for everyday tasks with the WREX.

Design and pilot validation of A-gear: a novel wearable dynamic arm support

BACKGROUND

Persons suffering from progressive muscular weakness, like those with Duchenne muscular dystrophy (DMD), gradually lose the ability to stand, walk and to use their arms. This hinders them from performing daily activities, social participation and being independent. Wheelchairs are used to overcome the loss of walking. However, there are currently few efficient functional substitutes to support the arms. Arm supports or robotic arms can be mounted to wheelchairs to aid in arm motion, but they are quite visible (stigmatizing), and limited in their possibilities due to their fixation to the wheelchair. The users prefer inconspicuous arm supports that are comfortable to wear and easy to control.

METHODS

In this paper the design, characterization, and pilot validation of a passive arm support prototype, which is worn on the body, is presented. The A-gear runs along the body from the contact surface between seat and upper legs via torso and upper arm to the forearm. Freedom of motion is accomplished by mechanical joints, which are nearly aligned with the human joints. The system compensates for the arm weight, using elastic bands for static balance, in every position of the arm. As opposed to existing devices, the proposed kinematic structure allows trunk motion and requires fewer links and less joint space without compromising balancing precision. The functional prototype has been validated in three DMD patients, using 3D motion analysis.

RESULTS

Measurements have shown increased arm performance when the subjects were wearing the prototype. Upward and forward movements were easier to perform. The arm support is easy to put on and remove. Moreover, the device felt comfortable for the subjects. However, downward movements were more difficult, and the patients would prefer the device to be even more inconspicuous.

CONCLUSION

The A-gear prototype is a step towards inconspicuousness and therefore well-received dynamic arm supports for people with muscular weakness.