Abstract
Background A person's ability to move his or her arms against gravity is important for independent performance of critical activities of daily living and for exploration that facilitates early cognitive, language, social, and perceptual-motor development. Children with a variety of diagnoses have difficulty moving their arms against gravity.
Objective The purpose of this technical report is to detail the design process and initial testing of a novel exoskeletal garment, the Playskin Lift, that assists and encourages children to lift their arms against gravity.
Design This report details the design theory and process, the device, and the results of field testing with a toddler with impaired upper extremity function due to arthrogryposis multiplex congenita.
Results The Playskin Lift is an inexpensive (<$30 material costs), easy to use (5/5 rating), comfortable (5/5 rating), and attractive (4/5 rating) device. While wearing the device, the child was able to contact objects more often throughout an increased play space, to look at toys more while contacting them, and to perform more complex interactions with toys.
Limitations This report details initial testing with one child. Future testing with more participants is recommended.
Conclusions These results suggest that by considering the broad needs of users, including cost, accessibility, comfort, aesthetics, and function, we can design inexpensive devices that families and clinicians can potentially fabricate in their own communities to improve function, participation, exploration, and learning for children with disabilities.
A person's ability to move his or her arms against gravity is important for independent performance of countless activities of daily living, such as feeding, dressing, and academics.1,2 Additionally, arm movement facilitates interaction with objects and surfaces for the purposes of safety (ie, holding a stair railing), exploration (ie, play with toys), mobility (ie, controlling mobility devices), and learning (ie, tool use).3,4 For young children, exploration using the arms significantly affects cognitive, language, social, and perceptual-motor development.5
It is not surprising that when children demonstrate impaired or delayed use of their upper extremities, they often display delays in other developmental areas. For instance, infants with later reaching onset and less object exploration are not as successful at exploring and problem solving.3,6 Children with a variety of diagnoses have impaired arm movement that limits their ability to function, play, and learn.5,7,8 For instance, infants born preterm or with neonatal stroke have difficulty sustaining and holding both hands together in midline to interact bimanually with objects.1,7 Children with hemiplegia have impaired control of the upper extremity contralateral to their brain injury and may have impaired control of the ipsilateral upper extremity.9,10 Children with brachial plexus palsy have unilateral weakness that limits use of their affected arm against gravity and may lead to associated deficits even after regeneration of the nerves.11 Children with arthrogryposis multiplex congenita (also known as arthrogryposis) often have weakness in both upper extremities that significantly limits arm movement even after their contractures have resolved.12 Therefore, a variety of pediatric populations could benefit from interventions aimed at improving arm function.
Therapeutic techniques such as isometric exercises, aquatic rehabilitation, and neuromuscular electrical stimulation can improve strength and motor control when an individual has impaired movement against gravity.13–15 However, these techniques may be challenging with young children who cannot follow complex instructions, have trouble with thermoregulation, or cannot provide reliable feedback about sensation.16 Interventions to improve strength and motor control for young children include weight-bearing activities, hands-on assistance from an adult, and positioning to encourage active movement in gravity-eliminated planes.17,18 When children have significant weakness, a high level of assistance and supervision may be required to ensure safe and effective performance of these activities. The result is that intervention is limited to brief times when the therapist or caregiver is available to work with the child. This is a serious problem because the most successful intervention programs are those that incorporate high doses and frequent opportunities for practice throughout each day similar to the pattern of activity observed during typical skill development.19,20 Rehabilitative technologies can aim to provide for activity and skill building with high doses of practice and less dependence on adult supervision and assistance.
The purpose of this report is to describe a novel exoskeletal garment, the Playskin Lift, which assists and facilitates antigravity movement and has the potential to serve as an effective, high-dose rehabilitation tool for individuals with arm movement impairments. An exoskeleton is a structure that is worn external to the body that mimics the human endoskeleton by assisting and supporting movement.21 The Playskin Lift was developed as a tool to improve function in young populations with weakness and poor motor control.
Below we describe the design model that guided our device development process and provide details about the fabric and mechanical components of the Playskin Lift. We then present data on the functional impact of the therapeutic garment within a single session for a toddler with arthrogryposis. Finally, we outline future design goals and needs for exoskeletons that may be used simultaneously as assistive devices to improve function and participation while being worn as rehabilitation devices that can be used for intervention to improve strength, function, and participation across time even outside of intervention periods when the device is removed.
Method
Design Motivation and Model
Our research team recently began working to adapt the Wilmington Robotic Exoskeleton (WREX; Fig. 1) for young children with arm movement impairments. The WREX is a 2-link exoskeleton that sits alongside the arm to support and assist movement against gravity at the shoulder and elbow joints.22 Composed of metal, 3-dimensional printed plastic, and rubber bands, the WREX attaches to a wheelchair or customized thoracic-lumbar-sacral orthosis (TLSO). The forearm rests in a trough secured using hook-and-loop straps. Rubber bands stretch across the shoulder and elbow joints to produce torque to help elevate the arms against gravity. The WREX has primarily been used clinically as an assistive device for adolescents with arm weakness, such as those with muscular dystrophy, to help them move their arms against gravity for function in a larger workspace.
The 3-dimensionally printed Wilmington Robotic Exoskeleton (WREX) on an infant. Rubber bands attach laterally to the device and cross the shoulder and elbow joints to provide torque to assist with flexion at those joints.
Our recent modifications have made the WREX smaller and lighter for use with young children. We recently completed the first single-subject study using the WREX for an 8-month-old infant with arthrogryposis. Although the child's arm function improved when he wore the WREX, the family discontinued using it after the study.
Four families of children with arthrogryposis who had obtained WREXs but discontinued using them helped us identify several key user needs not met by the device via informal interviews. Parents reported concerns about temperature regulation and skin breakdown from the TLSO, bulkiness (the TLSO and WREX do not fit in car seats, standers, high chairs, and other common pieces of equipment), inability to use the WREX while nursing and cuddling, and safety and movement limitations when exploring transitions, such as between sitting and supine and during rolling. Users and their parents reported that its appearance often drew unwanted attention. Although the WREX functioned to help lift the arms, these anecdotal reports suggested there were important limitations in how it affected performance of other behaviors, how it looked, and how it fit within users' everyday lives.
A successful rehabilitation device must be worn and used by clients in order to effect behavioral change. Creating such a device likely requires an interdisciplinary, user-focused design process. Therefore, we brought together a team of individuals with rehabilitation, engineering, or fashion expertise to work with children with disabilities and their families to design an exoskeleton that was safe, sleek, functional, comfortable, and embedded within a garment. The team consisted of: (1) 2 pediatric physical therapy professors with clinical, device design, and research experience; (2) 2 mechanical engineering professors, a mechanical engineering graduate student, and 4 senior undergraduate mechanical engineering students with design, prototyping, and modeling experience; and (3) a professor and instructor from fashion and apparel studies with textile testing, design, and fabrication experience.
We used the Functional, Expressive and Aesthetic Consumer Needs Model to guide our design process.23 This model provides a conceptual framework with which to assess the user-centered needs of products. When designing for the general public, functional, expressive, and aesthetic aspects are generally considered with similar importance. On the contrary, function is often the defining goal when designing products for individuals with disabilities. As such, key needs may be neglected with negative consequences, including lack of product use or social stigma associated with product use.23,24 For example, products may focus attention on users' disabilities via “adaptive” design elements, such as special closures, nontraditional materials, or oversized components.25 The Functional, Expressive and Aesthetic Consumer Needs Model highlights that clothing and devices for all users, including those with disabilities, should emerge from a design process that incorporates users throughout and focuses similar importance on fashion and functional needs.23 We wanted the Playskin Lift to function but also to be attractive and discreet to meet the psychosocial needs of young children and families.
Playskin Lift Exoskeletal Garment
Our interdisciplinary team created a new exoskeletal garment, the Playskin Lift, to assist arm lifting (Fig. 2). The Playskin Lift is a onesie or shirt made of 4-way stretch blended fabric (87% polyester, 13% spandex). The fabric was selected for comfort and close fit to support and properly align the mechanical components. Narrow strips of vinyl casings were stitched vertically along the garment's seams on either side of the trunk and under each arm, which created tunnels where we could place mechanical inserts to assist in lifting the arms. Vinyl was used because its thickness offers padding between the mechanical inserts and the child's skin. For ease of donning and doffing, the garment was designed with a medial zipper closure on the front. A knit fabric backing was constructed to shield the skin from getting caught in the zipper.
The Playskin Lift from the front (A), from the rear (B), on a mannequin (C), and on the participant in supine (D) and sitting to demonstrate how the device allows for shoulder extension (E) while assisting shoulder flexion (F). The mechanical inserts for the Playskin Lift (G) are made by bundling pieces of carbon steel music wire, covering them with heat-shrink wrap, and sealing the bundle ends with athletic tape and additional heat-shrink wrap. The amount and diameter of wire used to make each bundle determine the amount of lifting assistance that will be provided to the upper extremity.
We built 2 mechanical inserts, one for each arm. The inserts were made of carbon steel music wire, bundled in amounts proportional to the weight of the child's arm and the desired lift of 90 degrees of shoulder flexion, and covered in rubber heat-shrink tubing (Fig. 2G). The bundle ends were dressed in strips of athletic tape and covered again in rubber heat-shrink tubing to prevent perforation. The music wire was chosen for this design due to its strength, elasticity, and geometric properties. Mechanically, the wire inserts provide sufficient moment to lift the weight of the arms and place them at a flexed equilibrium position. Their elastic properties allow for the child to move into shoulder extension, and the cylindrical shape of the bundle allows for movement in other planes. The flexural rigidity of the steel can be customized to the person's size and weight by increasing or decreasing the bundle's capacity and the diameter of the individual wires.
In designing the Playskin Lift, our team adhered to federal safety standards for children's toys and clothing,26 so the final product did not include any small parts, drawstrings, or hazardous or flammable materials. In addition, we conducted safety testing on the mechanical inserts, including testing them to failure due to concern that the wire bundles might break and cut into the trunk or axilla. Testing revealed that the steel wires fail in a manner that results in kinking rather than breaking.
Participant
A 23-month-old with amyoplasia, the most common type of arthrogryposis, and his family participated in this study.27 His parents provided informed consent. As is common for children with amyoplasia, the toddler had a history of muscle fibrosis, decreased muscle mass, and shoulder, elbow, hip, knee, and ankle joint contractures, with the limbs affected in a symmetrical manner. Specifically, he was born with limited shoulder flexion and elbow flexion in both of his upper extremities. The toddler had typical trunk musculature and normal or above average cognition, as is common for children with amyoplasia.12,27,28 He was able to roll, sit independently, walk using a rolling walker, and transition independently from sitting to supine in a controlled manner without using his arms using controlled trunk extension. Cognitively, the toddler demonstrated age-appropriate interactions with his siblings and adults, such as following multiple step requests, demonstrating sustained attention for play activities, speaking using phrases with several words, and actively engaging with toys.
The toddler had a history of patent ductus arteriosus, patent foramen ovale, bilateral Achilles tendon lengthening (at age 4 months), ear tube placement (at 12 months), bilateral orthopedic hip surgery (at age 14 months), and orchidopexy surgery (at age 16 months). He received physical therapy 1 hour per week and occupational therapy 1 hour every other week since 3 months of age. He received speech therapy 1 hour every other week starting at 21 months. He had no other significant medical history.
Assessments
The toddler was visited once in his home. We used 2 camcorders to record all assessments. Videos were synchronized and analyzed using Datavyu behavioral coding software (National Science Foundation– and National Institutes of Health–supported open access software, http://datavyu.org).
Mechanical testing of the inserts.
A model was designed to determine insert sizes required to lift the arm 90 degrees based on the weight of the user (testing to determine wire moments is described in Fig. 3A). Wire moments were compared with expected shoulder moments based on anthropometric data for children from birth through 3 years of age.29 Shoulder moment was computed as the product of arm weight and distance to the center of mass assuming 50th percentile mass and height for boys in this age group and compared with experimental results from mechanical testing and field testing data for the current participant.
Modeling to determine insert sizes required to lift the arm to 90 degrees of shoulder flexion based on the weight of the user. The testing apparatus (A) emulated a solid trunk with a hinge joint and lightweight arm. Each insert was secured with an adjustable seam length (a and b) corresponding to wire segment length (X and Y). The wire was loaded until equilibrium was achieved at 90 degrees, and the resultant moment was computed as the product of load (W) and distance (c). The test was repeated with wire diameters of 0.020, 0.024, and 0.031 in (1 in=2.54 cm) and sets of 5, 10, or 20 wires per bundle. Figure 3B charts the number of wires that should be used for inserts to lift an arm to 90 degrees in relation to the joint moment and the child's weight. The plus sign corresponds to the data for the toddler in this report.
Device assessments.
To measure the effectiveness of the design, we assessed: (1) ease of use and profile, (2) manufacturing feasibility, (3) fabric performance, and (4) ability to meet the functional, expressive, and aesthetic needs of the user.
To assess ease of use and profile, we measured: (1) device donning and doffing time and (2) maximum radial length of garment extension from the skin. Donning and doffing were performed by the toddler's mother without instruction to determine intuitive ease of use. This was the mother's first experience with the device. Donning time began the moment the fabric contacted the toddler's skin and ended when both inserts had been placed in their tunnels. Doffing time was the reverse of these operations. Maximum radial extension of the garment was measured via a flexible tape measure as the perpendicular distance from the skin to the farthest protruding point on the fully donned garment.
To assess the manufacturing feasibility of the Playskin Lift, we measured material costs, fabrication time, and commercial availability of materials. Costs for tools (heat gun, sewing machine, wire cutters, snap press) needed to assemble the device were not included.
To assess fabric performance, experiments were conducted to assess variables related to comfort and durability (testing described in eTab. 1). The tests included measurement of thermal resistance, evaporative resistance, and stiffness or softness. These tests were performed to better inform us about the properties of fabrics that could function to support mechanical components and to provide information related to a key user need: temperature regulation. We performed these tests on 2 fabrics. The first fabric was used to make the initial prototype. We selected a performance stretch knit for the first fabric because we wanted a blend of stretch and tensile strength to provide a close fit to maintain alignment of the mechanical inserts while being comfortable for the user. We selected a second fabric for testing for 2 reasons. First, the first fabric was acquired from a commercially available athletic shirt that was discontinued after the season, which is typical for commercial clothing products. Second, the first fabric had 2 layers, a synthetic knit with fleece back, and, therefore, had the potential to be uncomfortable in warmer climates. We selected the second fabric to have a similar percentage of strength and elasticity while being thinner, a single layer, and readily available by the yard at a popular commercial establishment. The second fabric functioned and has been used for subsequent prototypes and testing.
To verify that the broader fashion needs of the toddler and family were met, the parent was provided with a questionnaire to complete after testing (Table). The purpose was to gauge the parent's perspective on comfort, ease of use, and appearance of the Playskin Lift. Questions were answered by the participant's mother via Likert scales.
Parent Perception Questionnaire Questions Posed to the Participant's Mother, Rating Scale, and Responses to Assess the Ease of Use, Comfort, and Attractiveness of the Playskin Lift
Behavioral assessments.
To assess whether the device improved function and play abilities, we performed 3 standardized behavioral assessments, each with the Playskin Lift off and again with the Playskin Lift on. The trained coder who coded these assessments had intrarater and interrater reliability >90% established with 2 other coders based on 20% of the data from a larger data set incorporating the same assessments. These assessments of reliability were based on a strict comparison of agreement using the equation: [(Agreed)/(Agreed + Disagreed)] × 100.7 Behavioral coding to show targeted changes in behaviors is a common method of analysis in developmental research and has been previously used by the authors.6–8,30 Assessments were performed continually within a session where the infant was in a positive behavioral state, awake, alert, and not crying. Throughout each assessment, the experimenter responded to social interaction from the infant by smiling but did not initiate social interaction and did not engage in play with objects.
The reaching location assessment measured ability to reach for and contact objects presented at varying heights. The toddler was provided 30-second opportunities to interact with objects at eye height, chest height, and hip height while seated on the floor both with and without the device. To begin trials, the experimenter moved the object to the target location, shook it to draw the infant's attention, and started the trial timer when the infant looked at the object. A trained coder blind to the study hypotheses reviewed and coded toy contact based on the start and end video frames for periods when any part of either hand was in contact with the toy. These data were then run through customized programs using Filemaker Pro Advanced software (Filemaker Inc, Santa Clara, California) to convert data to percentages of time.
The naturalistic play assessment involved sitting on the floor surrounded by toys that allowed for a variety of functions during 3 minutes of free play with and then without the device. The same trained coder who was blind to the study hypotheses coded each of the following variables:
Right hand– and left hand–supported contact with the toy: Start and end frames for periods when the toddler held a toy in the right or left hand while the toy was resting on something such as the toddlers' legs, the ground, or another object.
Right and left hand suspended contact with the toy: Start and end frames for periods when the toddler held a toy in the right or left hand while the toy was not resting on something.
Toy interaction: Start and end frames for periods when the toddler was playing with 2 or more toys, such as stacking toys, banging toys, or putting a toy into another toy.
Visual attention to toys: Start and end frames of periods when the child's eyes were directed at a toy for more than 1 second.
These data were then run through customized programs using Filemaker Pro Advanced software to determine when these behaviors overlapped in occurrence and to convert these data to percentages of time. This process allowed us to calculate the new variables “bilateral toy contact,” representing periods when the right and left hands contacted toys, and “toy contact while looking,” representing periods of multimodal exploration when toy contact and visual attention overlapped.
The mobility and transition assessment involved about 10 minutes of the experimenter encouraging the toddler to move about on the floor and around the house in his typical manner, about 5 minutes with and about 5 minutes without the device. The trained coder coded the types of transitions (ie, rolling, sitting to supine) and mobility (ie, scooting, walking) the toddler performed with and without the device. The goals were to observe one example of each type of transition and mobility the toddler could engage in without the device and to determine whether the child could still perform those behaviors at least once with the device donned.
Role of the Funding Source
This research was supported, in part, by The Eunice Kennedy Shriver National Institute of Child Health and Human Development (1R21HD076092-01A1) and by a University of Delaware UNIDEL grant.
Results
Mechanical Testing of the Inserts
Wire moment increased with wire diameter and bundle size (Fig. 3B). For the toddler in this study (age 23 months, weight 10.9 kg), a shoulder moment of approximately 0.9 N·m was expected to lift the arm to 90 degrees of shoulder flexion based on the anthropometric data and a total wire length of 300 mm with equal trunk and arm segment lengths (a=b=160 mm). This was achieved via an insert with 10 wires of 0.079 cm (0.031 in) diameter.
Device Assessments
Ease of use and profile of the device.
The device was generally low profile and easy to use. Uninstructed, the parent was able to independently don the device for the first time in just over 2 minutes (126.1 seconds) and to doff the device in less than a minute (40 seconds). The maximum radial extension of the device from the skin was 3.175 cm (1.25 in) in the axilla where the mechanical inserts bent from the weight of the arm.
Manufacturing feasibility of the device.
The device has high feasibility for manufacturing. Fabrication of the garment portion of the device required 6 hours for sewing, fitting, and adjustment by an experienced tailor. Fabrication of each mechanical insert required 5 minutes. Materials were inexpensive (total cost of $29.54; eTab. 2) and widely available at large retail stores and pharmacies and online.
Fabric performance.
Fabric testing results are provided in eTable 1. As noted in the Method section, fabric testing was performed on 2 different fabrics that were used to create versions of this garment. Both fabrics had the appropriate level of stretch to function for this exoskeletal garment. However, the second fabric had a higher tensile strength; was thinner, softer (lower stiffness), and more breathable (lower evaporative resistance); and would likely feel cooler (lower thermal resistance). Therefore, not only is the second fabric more readily accessible to consumers, but it also should be more comfortable, especially in warm weather conditions.
Ability of the device to meet the functional, expressive, and aesthetic needs of the user.
According to our Parent Perception Questionnaire results (Table), the participant's mother generally found the garments very easy to don and doff and the inserts easy to insert and remove. She perceived her child to be very comfortable in the device in the first few minutes, after 15 minutes, after 1 hour, and after 1.5 hours of continual wear. She rated the overall appearance of the Playskin Lift as somewhat attractive.
Behavioral Assessments
Reaching location behavioral assessment.
The toddler showed improved ability to reach for and contact toys while wearing the Playskin Lift (Fig. 4). Without the garment, the toddler only contacted objects presented at his hip level. When wearing the garment, he also was able to contact objects that were presented at his chest and eye levels. Furthermore, he spent more time contacting objects at hip level.
Percent time during the reaching location assessment that the participant was able to contact a toy presented at hip level, chest level, and eye level while seated with the Playskin Lift on or off. Note that the participant was motivated and successful interacting with the toy at hip level but was not able to contact the toy at chest and eye level with the garment off. When wearing the Playskin Lift, he was able to contact toys more often at hip level and was able to contact toys at chest and eye level.
Naturalistic play assessment.
The toddler showed improved ability to sit on the floor and play with toys while wearing the Playskin Lift (Fig. 5A). Without the garment, the toddler used his right hand to contact toys about 50% of the time, rarely used his left hand (<2% of the time), and never showed bilateral contact. When wearing the garment, he increased the time he contacted toys with his right hand (from 53.5% to 64.3%) and greatly increased the time he contacted toys with his left hand (from 1.7% to 58.0%). He also started to show some bilateral contact (5.5% of the time). Much of his toy contact involved supporting, or resting the toy on his body or surfaces, but he also demonstrated more suspended, or unsupported, contact while wearing the garment.
Results of the naturalistic play assessment, playing with toys while seated on the floor. When wearing the garment, the participant had improved ability to hold toys with and without support from a surface (supported and suspended contact, respectively) with the right hand, left hand, and with both hands (A). Note the large increase in holding with the left hand and the appearance of bilateral holding when wearing the Playskin Lift. Not only did the Playskin Lift improve the participant's ability to contact and hold toys during floor play, but the participant looked at objects more while contacting them and spent more time performing interactive behaviors with objects when wearing the garment (B).
The toddler also showed improved interaction with the toys for play and multimodal exploration using vision and touch when wearing the Playskin Lift (Fig. 5B). He spent more time interacting with multiple toys for stacking, banging, and putting toys in and out of one another when wearing the device (12.4%) than without it (2.7%). He spent more time looking at toys while contacting them when wearing the device (73.9%) than without it (46.4%).
Mobility and transition assessment.
The toddler's mobility and transition skills were delayed but did not differ with and without the device. This finding suggests that the device did not restrict him from engaging in these typical behaviors. He was observed independently transitioning from sitting to supine and rolling from supine to prone and prone to supine once with and once without the device.
Discussion
Summary of Findings
Our team of rehabilitation, engineering, and fashion experts was able to design an inexpensive, low-cost garment exoskeleton for a toddler with arthrogryposis. The garment met many of the needs of families who use upper extremity exoskeletons. For instance, the Playskin Lift is inexpensive, easy to don and doff, comfortable, and low profile so it could fit in the equipment families use each day for their young children. The parent was pleased with the ease of use, comfort, and appearance of the device during the testing session. Functionally, the device effectively improved the toddler's ability to reach and play with toys within the testing session, specifically increasing his play space, contact time with objects, bimanual reaching, multimodal play, and engagement and interaction with multiple objects.
Playskin Lift: An Important Model for the Development of Real-World Rehabilitation Devices
The design process detailed here provides a model for how interdisciplinary teams can work with users throughout all aspects of the design process to create a “real-world rehabilitative device.” The term “real-world rehabilitative device” signifies one that people actually want to wear, that functions, and that expresses individuality rather than accentuating disability.31 We propose it is critical that designers not only consider the function of devices under development but also listen to and incorporate the broader psychosocial needs of the users who will be choosing whether to incorporate these devices into their everyday lives.32 Considering the broad needs of users, and not simply device function, increases the probability that devices will be used for high doses of movement practice and thus will more likely facilitate behavioral change and enhance learning for users.10
In addition to introducing a new model for rehabilitative device development, this report also illustrates the potential to change the way rehabilitative devices are manufactured and disseminated.33 Instead of selecting from a limited supply of expensive devices from medical companies, we can empower users across the globe to use, modify, and even create their own online instruction manuals and videos so users and members of the community can make their own devices.34 This type of community engagement and empowerment is possible when we create safe, effective, and sophisticated, yet low-tech, designs using readily available, inexpensive materials.35,36
Potential Applications for the Playskin Lift
The Playskin Lift and similar therapeutic garments have the potential to affect the function of individuals with a variety of diagnoses by serving as assistive or rehabilitative devices. For example, they may be useful as assistive devices, with the goal of supporting movement or postural control in order to increase independence for individuals with significant weakness due to diagnoses such as spinal muscular atrophy, muscular dystrophy, or amyotrophic lateral sclerosis.21,22,37 In addition, exoskeletons may serve as rehabilitative devices, with the goal of improving motor control, coordination, strength, and function for individuals after nervous system injury, such as stroke, hemiplegia, or brachial plexus palsy, or for individuals with diagnoses associated with significant weakness, such as arthrogryposis or Down syndrome.38–40 In these cases, the amount of assistance provided by the device can be progressively altered across time to match the changing ability of users similar to the progression observed with therapeutic exercise. The goal is to provide progressively less assistance as users demonstrate improved movement ability. Consequently, the devices could be used in intervention to provide just the right level of assistance and challenge for each user with the end goal of improving the user's function, participation, and independence even when the device is not being worn.
Need for Further Design Modification and Testing
The Playskin Lift has undergone multiple design iterations to achieve its present state; however, several aspects need improvement. First, function can be improved by designing ways to support movement at more joints. The device currently assists movement at the shoulder. Many infants and children with impaired shoulder mobility also experience impaired elbow mobility or poor head control.12,41 Expansion to other joints may further facilitate independent performance of activities of daily living for children.
Second, comfort may be improved by replacing the current fabric with a material that is thinner, softer (lower stiffness), and with lower thermal and evaporative resistances. We predict that this type of material would improve the user's experience in warm climates. Moreover, integrating multiple types of fabrics or trimming down excess material without compromising the function of the Playskin Lift also may improve overall comfort.
Third, aesthetics and expressiveness can be improved by expanding the form of the garment beyond the current designs. Fabric color, texture, and embellishments as well as garment form (shirt, onesie, jacket, or swimwear, for instance) could reflect the preferences of users. These improvements may provide users and other team members with greater flexibility of design choices.
Fourth, in terms of user control and design, a limitation of the exoskeletons currently available (WREX and Playskin Lift) is that they are passive devices, meaning they do not dynamically change their level of assistance based on the needs of users without outside assistance. Furthermore, users cannot typically independently don them or set the level of assistance they desire.21 For example, users of the WREX need someone to place the rubber bands that will assist their arm movements, and users of the Playskin Lift need someone to place the mechanical inserts in their garment. Future versions of these exoskeletons should focus on providing users with control mechanisms whereby they can independently move among a range of levels of support.42–44
Finally, it needs to be determined whether this device can be effectively used for daily interventions that aim to improve function when the device is no longer worn. This usage involves determining whether users can safely and comfortably wear the device for daily intervention in the natural environment. Because the device incorporates materials that are common in commercially available garments and it does not have small parts, it likely poses hazards similar to those accompanying typical clothing items or orthotic devices. As with all such items, there is a need for adult monitoring during use. Users should be advised how to check that circulation and skin integrity are not impaired when the garment is worn. Once we test whether the device is comfortable and durable for extended daily use, we need to assess whether intervention with the device can change function across time for children with impaired upper extremity function.
Conclusion
Exoskeleton devices, including the Playskin Lift, appear to be promising assistive and rehabilitative devices for a variety of populations. Research and development can now focus on if, how, and when they can be used as effective assistive devices and rehabilitative devices across larger samples of a variety of clinical populations. Studies should address scalability, application across joints, dosage, and impact on function and participation. They also should involve counterbalancing the condition (device on, off) to address order effects, such as learning within a session, habituation, or fatigue.
Footnotes
Dr Lobo, Mr Koshy, Ms Hall, Dr Buckley, and Dr Galloway provided concept/idea/research design. Dr Lobo, Mr Koshy, Ms Hall, Mr Erol, and Dr Galloway provided writing. Dr Lobo, Mr Koshy, Ms Hall, Mr Erol, and Dr Cao provided data collection. Dr Lobo, Mr Koshy, Ms Hall, Mr Erol, Dr Cao, Dr Buckley, and Dr Higginson provided data analysis. Dr Lobo and Dr Buckley provided project management. Dr Lobo and Dr Galloway provided fund procurement. Dr Lobo provided participants. Dr Lobo, Dr Cao, and Dr Buckley provided facilities/equipment.
This project was approved by the Institutional Review Board at the University of Delaware.
This research was supported, in part, by The Eunice Kennedy Shriver National Institute of Child Health and Human Development (1R21HD076092-01A1) and by a University of Delaware UNIDEL grant.
- Received December 8, 2014.
- Accepted August 18, 2015.
- © 2016 American Physical Therapy Association
References
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