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Research Papers

Adapted Motor-Assisted Elliptical for Rehabilitation of Children With Physical Disabilities PUBLIC ACCESS

[+] Author and Article Information
Judith M. Burnfield

Institute for Rehabilitation
Science and Engineering,
Madonna Rehabilitation Hospitals,
5401 South Street,
Lincoln, NE 68506
e-mail: jburnfield@madonna.org

Thad W. Buster

Institute for Rehabilitation
Science and Engineering,
Madonna Rehabilitation Hospitals,
5401 South Street,
Lincoln, NE 68506
e-mail: tbuster@madonna.org

Chase M. Pfeifer

Institute for Rehabilitation
Science and Engineering,
Madonna Rehabilitation Hospitals,
5401 South Street,
Lincoln, NE 68506
e-mail: cpfeifer@madonna.org

Sonya L. Irons

Institute for Rehabilitation
Science and Engineering,
Madonna Rehabilitation Hospitals,
5401 South Street,
Lincoln, NE 68506
e-mail: sirons@madonna.org

Guilherme M. Cesar

Institute for Rehabilitation
Science and Engineering,
Madonna Rehabilitation Hospitals,
5401 South Street,
Lincoln, NE 68506
e-mail: gcesar@madonna.org

Carl A. Nelson

Department of Mechanical and
Materials Engineering,
University of Nebraska-Lincoln,
W316 Nebraska Hall, P.O. Box: 880526,
Lincoln, NE 68588
e-mail: cnelson5@unl.edu

1Corresponding author.

Manuscript received February 7, 2018; final manuscript received September 12, 2018; published online December 4, 2018. Assoc. Editor: Elizabeth Hsiao-Wecksler.

J. Med. Devices 13(1), 011006 (Dec 04, 2018) (9 pages) Paper No: MED-18-1027; doi: 10.1115/1.4041588 History: Received February 07, 2018; Revised September 12, 2018

Many children with physical disabilities experience difficulty using traditional exercise equipment for gait rehabilitation and fitness training, and the clinician resources required to deliver intensive overground or treadmill-based therapies are infrequently available in most clinics, hospitals, and school settings. This work describes design and testing of a comprehensive set of modifications that enabled children to use a commercially available robotic exercise device (i.e., Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE)) initially developed to address walking and fitness goals of adults with physical disabilities and chronic conditions. Fifteen children (3–11 years old) concurrently enrolled in physical therapy due to varied neurologic conditions were recruited with their parent(s) to evaluate the safety, comfort, and usability of the adult ICARE and pediatric-modified ICARE. After children tried each device, feedback was recorded. To assess feasibility, each child then participated in up to ten sessions (two to five sessions per week; average session length: 38 min, range 21–66 min) using the pediatric-modified ICARE. Parents, on average, perceived that the pediatric-modified ICARE was significantly safer, more comfortable and usable than the adult ICARE. Children's perceptions of the pediatric-modified ICARE were similar, although not statistically significant. Children used the prototype device during 133 sessions for over 3800 min and more than 162,000 cycles. In conclusion, this study demonstrated the feasibility of using the pediatric-modified ICARE with children as young as 3 years old as an adjunct to ongoing therapy.

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Limitations in strength, balance, sensation and endurance make it difficult for some children with physical disabilities to use traditional exercise equipment for gait rehabilitation and fitness training, and the clinician resources required to deliver intensive overground or treadmill-based therapies are infrequently available in most clinics, hospitals, and school settings. Robotic gait trainers reduce labor demands, but cost of the technology impedes widespread use. The lack of equipment to address the needs of children is concerning because involvement in moderate levels of sustained exercise helps increase strength, flexibility, cardiovascular fitness and function, and also prevents/delays the onset of other chronic conditions [15].

A growing number of rehabilitation, fitness, and home settings are using the Intelligently Controlled Assistive Rehabilitation Elliptical (ICARE), a commercially available motor-assisted elliptical, to improve walking and fitness of adults and adolescents impacted by a wide range of conditions and illnesses (Fig. 1). Compared to other ellipticals, the device promotes a movement pattern that more closely simulates the joint motions and muscle demands of gait [6] while also providing a customizable level of assistance from a motor that enables users to train at speeds up to 65 cycles per minute (CPM) in either forward or reverse directions [7,8]. When users exceed the set-speed, the motor disengages, challenging the user to sustain the movement on their own [9]. Speed, body weight support (BWS), level of motor-assistance/resistance, and step length can be customized to address the unique gait and cardiorespiratory training requirements of users with a wide range of impairments [9]. Low attrition and positive gains in walking and fitness in adults with neurologic disorders following ICARE use have been promising [912].

One challenge with the ICARE is that the device was not initially designed for use by younger/smaller pre-adolescent children [13]. For example, the average step length of 3–12 year old children ranges from as short as 35 cm to as long as 61 cm (the upper limit closely approximating the 71 cm step length of adults) [14,15]. However, as originally designed, the need for a shorter step length was not accommodated. Our team addressed this challenge, in part, by creating a modified crank mechanism that enabled the variable step length to be reduced to address the needs of children as young as 3 years old [16]. Although the modified crank mechanism addressed one obvious barrier to use by younger children, multiple barriers remained that were evident given knowledge of published anthropometric data, our team's observations of clinicians attempting to use the device with younger children, and previous feedback from clinicians and parents (Table 1). For instance, children's shorter leg length (average length of 3 year old = 47 cm versus adult = 90 cm) [1720] and narrower pelvic width (average width of 3 year old = 17 cm versus adult = 32 cm) [1720] resulted in young children's legs being more abducted when standing on the pedals compared to adults. The shorter leg length also made it difficult for some to get on and off of the device and seat. Likewise, the shorter height of younger children (average height of 3 year old = 83 cm versus adult = 169 cm) [1720] made visualizing and interacting with the control console challenging for some, while shorter upper extremity length (average 3 year old shoulder to wrist length = 47 cm versus adult = 56 cm) [1720] made it difficult to use the reciprocally moving handles, and smaller hands (average 3 year old hand length = 11 cm versus adult = 18 cm) [1720] made grasping some handles challenging.

This work describes the design of a comprehensive set of ICARE modifications that enabled children as young as 3 years of age to use the device and includes data from a pilot study that assessed feasibility of using the pediatric-modified ICARE as an adjunct to ongoing physical therapy in children with limited function arising from a wide range of underlying diagnoses. This work addresses the need for affordable pediatric equipment that adjusts to not only the changing therapeutic needs of a diverse patient population but also the range of body sizes.

Participants.

Fifteen children (3–11 years old) concurrently enrolled in physical therapy (n = 3 inpatient, n = 7 outpatient, n = 5 school based therapy) due to varied neurologic conditions were recruited from Madonna Rehabilitation Hospitals (Lincoln, Nebraska Campus) and the surrounding community with their parent(s) to participate in a study evaluating the safety, comfort, and usability of the ICARE and pediatric-modified ICARE (Table 2). Children with varied diagnoses, functional abilities, and ages were purposefully sought to capture the diversity representative of the characteristics of children who might ultimately use the pediatric-modified ICARE device.

Instrumentation.

Each participant provided feedback on the unmodified E872MA ICARE motor-assisted elliptical trainer (SportsArt, Woodinville, WA) as well as an E872MA ICARE that had been modified for use by children as young as 3 years old. Details of the unmodified and modified devices are provided below, as well as information about the harnesses used to support body weight and the instrumented walkway used to quantify walking speed.

Unmodified Motor-Assisted Elliptical.

The unmodified ICARE system included a ramp (13% grade), platform (H = 20 cm; L = 136.5 cm; W = 114 cm), two stairs (each ∼10 cm high), and an electronically height adjustable, manually pivoting seat (90 deg left and right) to ease access to the device. Seat height could be adjusted from 47 cm to 77 cm above the average height of the pedals. The front of the seat was positioned 16 cm posterior to the average anterior–posterior position of the pedals. The pedals (L = 40 cm; W = 19 cm) were spaced ∼10 cm apart (i.e., distance between medial borders of pedals) and included adjustable Velcro (Velcro, London, UK) strapping and elastic wraps to help position the feet. Step length could be adjusted electronically from 46 cm to 74 cm using buttons located on the console and on the reciprocally moving handles. The main control console (42 cm wide by 40 cm high) was positioned with its lower edge approximately 110 cm higher than the average pedal height. In addition to starting and stopping the device and controlling speed and step length, the console also provided a summary of select data (e.g., total time using device, speed, and step length). Speed could also be adjusted using the device's tethered remote control. Motor-assisted training could be performed at speeds up to 65 CPM in either the forward or reverse direction. When the user's training speed exceeded the set-speed, the motor disengaged. Although the device included a variety of traditional elliptical resistance modes, these modes were not assessed given the physical abilities of the children. Three handholds were available: a stationary triangle (∼89 cm above pedals), a handle-bar (adjusted from ∼71 cm to 103.5 cm above pedals), and reciprocally moving set (tops located ∼140 cm above pedals and traversed 32 cm to 46 cm in the anterior–posterior direction depending on step length setting). An integrated BWS system was capable of supporting up to 205 kg of body mass.

Pediatric Adaptations for Motor-Assisted Elliptical.

A separate E872MA ICARE motor-assisted elliptical trainer (SportsArt, Woodinville, WA) was adapted with a set of modifications that were iteratively refined over a 2 year period prior to the start of this study to address the needs of children as young as 3 years of age. Modifications were developed based on anthropometric and gait data from published literature, [17,18] in combination with ongoing feedback from a consumer advisory council we had assembled consisting of parents of children with disabilities, clinicians, and researchers, as well as manufacturer input, formal brainstorming by members of the research team, early pilot testing of prototype versions of the technology with children with and without disabilities, and unstructured interviews and feedback from children and parents during early prototyping efforts. The set of pediatric modifications (Table 1) tested in the current study are described below.

Modified seat: To reduce the footprint of the ICARE system and ease access for children, a commercially available Bruno Valet® Plus (Model VSS-2602) automobile seat was integrated with the ICARE. This required structural adaptations to affix the commercial seat to the ICARE, anti-tip bars to prevent the ICARE support system from tipping laterally during elevation of heavier users (the seat's lift capacity is 168 kg), and a power source for operating the automobile seat. Once installed, users were able to access the seat from either their wheelchair or a standing position. Depressing a control button caused the seat to lift, retract over the ICARE's base, and rotate the user to face forward in preparation for device usage (Fig. 2). The seat also translated anterior/posterior, allowing users' feet to be positioned over the pedals before standing. Collectively, these adaptations reduced the ICARE's footprint by eliminating the need for the ramp and platform.

Pedal height adjustability: To enable children to see and interact with the control console, a height adjustable pedal was integrated. A power drill could be used to adjust a screw-driven jack (ZENY Motorcycle Lift; ZENY Products, Rancho Cucamonga, CA) and vertically raise each foot pedal 38 cm (15 in) from the original ICARE's pedal height. The load capacity of each jack (500 kg) exceeded the needs of children and adults who would use the device as well as the ICARE manufacturer's load limit specifications. The pedals could be lowered to approximate the original pedal height when directly mounted to the ICARE frame. The inferior surface of the jack was attached to the pedal mounting surface of the ICARE with four bolts (Fig. 3). Similarly, each ICARE pedal was attached to the superior surface of a jack with four bolts.

To confirm that the modified pedal mounting did not significantly alter the trajectory of the pedal, a kinematic analysis was performed. Reflective markers were affixed to the lateral side of the right pedal (anterior and posterior) and kinematic data were recorded (Qualisys Motion Capture system, nine Oqus 400 series cameras; 200 Hz) while the ICARE cycled at 35 CPM at a step length of 61 cm (24 in). Data were recorded with the pedal set at 33 cm (13 in) on the screw-driven pedal jack mount and then again with the pedal mounted in the traditional ICARE mount position. Eight strides of data were averaged for each mounting position (raised and traditional) and for each reflective marker (anterior and posterior) to create representative trajectories (Fig. 4). The coefficient of multiple correlations statistic [21] compared the sagittal plane kinematic waveforms generated when the pedal mount was set at the highest position to those arising during the traditional ICARE pedal mount. After normalizing for the differences in pedal height, each comparison revealed a coefficient of multiple correlations value that exceeded 0.99, indicating a high level of similarity between the waveforms (note: a value of zero reflects highly dissimilar patterns, while a value approximating one suggests high similarity).

Greater step length adjustability: To accommodate the shorter legs and step length of young children, including those who might have hip flexion contractures/tightness, an adjustable crank mechanism was created [16] to replace the ICARE's original fixed length crank (Fig. 5). Crank length could be adjusted by turning a screw. Horizontal displacement ranged from 19 to 71 cm with the new adjustable crank versus 46–74 cm with the traditional crank. Likewise, step height (vertical displacement of a marker placed on the anterior pedal) could be as small as 5 cm with the adjustable crank versus a minimum of 12 cm with the traditional crank.

Step width adjustability: To reduce the interpedal distance so that young children's legs were not abducted excessively during use, the pedal mountings were modified. Specifically, a mounting plate with bolt slots was added to each mounting point between the pedal and elliptical interface that allowed the frontal plane distance between medial pedal borders to be adjusted from 2.5 to 15 cm compared to the previously fixed position of 10 cm (Fig. 6).

Pedal-integrated ankle-foot orthosis: It was expected that some children using the device might have calf weakness that would limit their stability and endurance during training. To address this challenge, our team integrated an ankle-foot orthosis (AFO) with each pedal. The resulting pedal-integrated AFO consisted of a stirrup that attached the brace to the pedal via a dovetail joint (Fig. 7). The pedal-integrated AFO could translate anterior-posterior relative to the pedal and was removable. Two height adjustable metal uprights attached to the stirrup through the device's ankle joint. Set screws, located in the anterior and posterior channels of the device's ankle joint, enabled customization of dorsiflexion/plantar flexion range during use. Set screws in the metal uprights could be adjusted to change the height of the calf strap. The adjustable calf band used Velcro (Velcro, London, UK) to secure an appropriately sized 3D printed insert around the anterior shin for a stable and comfortable circumferential fit.

Modified reciprocally moving handles: A new set of handles was created and attached to the existing reciprocally moving handles to make it easier for children to reach and use the handles. The handles were fashioned from polyvinylchloride (PVC) including piping (3.8 cm diameter), a 90 deg slip elbow, and an end cap. To improve comfort and slip resistance of the grip, the PVC was coated in rubber (Plasti Dip, Blaine, MN). The modified handle was attached to the existing reciprocally moving handles using a 3D printed handle interface. The PVC addition extended 15 cm perpendicular and 30 cm inferiorly to the existing reciprocally moving handles (Fig. 8). This brought the handles closer so children who had shorter arms or stature did not need to lean excessively forward or stretch upward when using the handles.

Console adaptation for use of tablets: A mounting system was designed to permit clinicians and parents to integrate tablet-based activities (e.g., educational apps or videos) when children used the ICARE (Fig. 9). The device was composed of a ball bearing sliding system with set-screw adjustability, a commercially available tablet holder (RAM Tab-Tite; RAM Mounts, Seattle, WA), and a friction hinge. The tablet holder safely held different sized tablets, ranging in width from 20 to 30 cm with heights up to 21 cm. The sliding system and friction hinge allowed the tablet to be raised and lowered easily, thus enabling adjustment for users of different heights and also facilitating access to the underlying control console.

Safety Harnesses Used With Children.

The ICARE's BWS system integrates with a variety of safety harnesses. Given past experience with various harnesses, our team elected to use Maine Anti-Gravity System harnesses (695 SHBD MAGS Suspension Vest; Main Anti-Gravity Systems, Inc., Portland, ME). Four sizes were required: pediatric, extra-small, small, and medium.

Instrumented Walkway.

Temporal and spatial stride characteristics were measured during overground walking using the GAITRite® Platinum electronic walkway (CIR Systems Inc. Clifton, NJ). The overall dimensions of the walkway are 574 cm long and 90 cm wide with an active recording region of 490 cm by 61 cm. Gait data were recorded at a frequency of 120 Hz.

Procedures.

The research study and informed consent were approved by the Institutional Review Board at Madonna Rehabilitation Hospitals, and all testing occurred in the Institute for Rehabilitation Science and Engineering. Following informed consent and assent, and prior to initiating testing, a parent or legal guardian completed a Medical History Screening Form and the Physical Activity Readiness Questionnaire for Everyone (PAR-Q+) for their children. Information recorded on these forms was used to screen for any potential medical conditions that might increase the risk associated with a child's participation (e.g., congenital heart disease, unstable healing fracture). Physician clearance was obtained when notable conditions were identified. After completing the questionnaires and obtaining physician clearance, basic anthropometric measurements were recorded including height and weight.

Feedback on ICARE and Pediatric-Modified ICARE.

Next, parents and children were asked to provide feedback regarding the unmodified and pediatric-modified ICARE devices (Fig. 10). First, each child had an opportunity to try the unmodified ICARE with and without the motor's assistance. Then, parents and children were asked to complete a series of visual analog scale (VAS) questions regarding their perceptions of the device's safety (with zero representing “not safe at all—my child would get injured if someone weren't here” versus 100 representing “very safe—my child could use the equipment without worrying about injury”), comfort (“not comfortable at all” versus “very comfortable”), and usability (“my child wouldn't want to use it—it's useless for him/her” versus “my child would really want to use it—it's ideal for him/her”). Qualitative input was also sought regarding suggestions to improve safety, comfort, and ease of use. This procedure was then repeated with the pediatric-modified ICARE.

Feasibility of Using Pediatric-Modified ICARE to Augment Physical Therapy.

Following the feedback session, each child was scheduled for up to ten sessions (two to five per week; average session length: 38 min, range 21–66 min) on the pediatric-modified ICARE to assess the feasibility of using the device with children of differing functional abilities. The pediatric-modified ICARE was used as an adjunct to existing therapy and no attempt was made to ensure that each child received the same number of sessions. The initial settings (i.e., pedal height, stride length, handle, cycling speed, and level of motor-assistance) were guided based on preferred settings during the previous feedback session. Subsequent sessions were adjusted to the unique needs of each child.

Data Management and Analysis.

Visual analog scale data from three children who were unable to communicate and four children who did not demonstrate the cognitive capacity to understand the scale were not included in the analysis. The remaining quantitative and qualitative data (15 parents, 8 children) were exported from the selectsurveyversion 2.3.4 software to an Excel (Microsoft Corp, Redmond, Washington, DC) spreadsheet for subsequent analysis. Descriptive statistics were performed for the quantitative VAS scores with sigma-plot 11.1 software (Systat Software Inc, Chicago, IL) and Excel. Assumptions of normality for the VAS data were screened with the Shapiro-Wilk test. If assumptions of normality were met, paired samples t-tests were performed separately for parents' and children's responses to determine whether the modifications had an impact on overall perceptions of safety, comfort, and usability of the pediatric-modified device compared to the unmodified device. If assumptions of normality were violated, the nonparametric equivalent Wilcoxon Signed-Rank test was used. Statistical significance was defined as p < 0.05. Range of scores and the 95% confidence intervals of differences were calculated. The qualitative, free-text responses were reviewed by research team members to identify themes relevant to improving the safety, comfort, and usability of the adult ICARE and pediatric-modified ICARE.

Feedback on Intelligently Controlled Assistive Rehabilitation Elliptical and Pediatric-Modified Intelligently Controlled Assistive Rehabilitation Elliptical.

Parents and children provided feedback on the perceived safety, comfort and usability of each device. Additionally, input was sought related to ideas to improve the design of each device.

Quantitative Comparisons Between Adult and Pediatric-Modified ICAREs.

Not unexpectedly, parents, on average, perceived that the pediatric-modified ICARE was significantly safer, more comfortable and usable than the adult ICARE (Table 3). Across categories, children (n = 8, given communication and comprehension challenges) rated the pediatric-modified ICARE an average of 37% higher than the ICARE; however, these improvements were significant only for the usability category.

Recommendations for Improving Each Device.

The most common parental suggestion to improve safety, comfort and usability of the adult ICARE related to lowering the console and handlebars (n = 20 comments across categories). In contrast, the comment was provided only once when the pediatric-modified ICARE was used. Parental recommendations to make the adult ICARE smaller (n = 19) and to shorten the step length were frequent (n = 17), yet were not identified as areas of concern for the pediatric-modified ICARE. Numerous parental comments were received regarding the adult ICARE's pedals being too large (n = 10), spaced too widely in the frontal plane (n = 4), and the pedal straps not being ideal for securing young feet to the pedals (n = 6); however, these concerns were notably less frequent with the addition of the pediatric modifications (n = 4, 2, and 3 comments, respectively). Multiple comments highlighted challenges experienced by young children when transferring onto the adult ICARE (n = 5) and accessing the device's height adjustable seat (n = 4), but these concerns decreased notably when using the pediatric-modified device (n = 1 recommendation to lower the seat). Although not identified as a challenge with the adult ICARE, six comments pertaining to improving grasp of the upper extremity handles were received for the pediatric-modified ICARE. The safety, comfort, and usability of the commercial harness that each child wore during evaluation was a point of notable concern across both the adult ICARE (n = 11) and the pediatric-modified device (n = 14). When queried if their child would use the ICARE if available, only 6 of 15 parents indicated “yes.” In contrast, 14 of 15 parents indicated their child would use the pediatric-modified ICARE if available. At the beginning of one child's involvement, a pedal loosened and made an undesirable noise resulting in the parent expressing short-term “concerns for child's safety and risk of injury” as the reason they would not use the prototype pediatric-modified ICARE. However, once the pedal problem was resolved (before next session), the parent and child completed the intervention study.

Children provided only 11 responses after using the adult ICARE and ten responses following use of the pediatric-modified ICARE. Similar to parental input, the majority of children's feedback (55%) on the ICARE was related to the size of the device. No feedback was provided regarding the size of the pediatric-modified ICARE. While only one child indicated need for improvement on the harness after using the ICARE, feedback related to the harness was suggested four times (40%) after children used the pediatric-modified ICARE. Only two children indicated they would use the ICARE if available, while nine indicated they would not. In contrast, eight children indicated they would use the pediatric-modified ICARE if available, while two indicated they would not. While one child provided the reason “because” the other child did not provide a rationale.

Feasibility of Using Pediatric-Modified Intelligently Controlled Assistive Rehabilitation Elliptical to Augment Physical Therapy.

Participants engaged in an average of 8.9 pediatric-modified ICARE sessions that were provided as an adjunct to their ongoing therapy (Table 4). The total time each child used the device varied from 43 min (performed across two sessions) to 373 min (completed across ten sessions). Thirteen children over-rode the motor for a portion of their sessions. The greatest proportion of time spent over-riding the motor (21%) was performed by an 11 year old child with cerebral palsy. Two were unable to over-ride the motor and also did not appear to understand the instructions/goal. Participants' step lengths while using the device ranged from 25.4 cm (10 in; used by a 4 year old) to 44.5 cm (17.5 in; employed by an 11 year old). Pedal elevation (referenced to the traditional pedal height) ranged from as much as 35 cm (13.8 in; used by the youngest) to only 5 cm (2 in, the minimum available given mounting hardware; used by an 11 year old child). The total number of strides recorded across sessions ranged from 1400 (child with encephalitis across two sessions) to 16,911 (child with genetic disorder across ten sessions).

Given the relatively small percentage of children with ambulatory deficits (less than 1% of the U.S. population between the ages of 5 and 17 years) [22] and the broad range of body anthropometrics, it is not unexpected that development of affordable robotic gait technologies for this population has been limited. As a result, many children with gait disorders lack access to effective and affordable exercise equipment that specifically targets muscles and motions required for walking while simultaneously promoting cardiovascular fitness. Without adequate training, it is difficult for many children to keep up with family and peers during outings and in school. Children may also be deprived of exercise's broader benefits on health, wellness, muscle and bone strengthening, and emotional well-being [23].

Success developing the ICARE provided a natural foundation for subsequent work developing a prototype affordable robotic device for young children. The team had initially considered creating a separate device specifically for younger, smaller children. However, subsequent discussions with clinicians and special educators pointed to the potential limitations of this approach. In particular, clinics and schools often care for children of varying ages and body sizes. Given financial and space limitations, most expressed a preference for a unified device that addressed the broad range of body anthropometrics and functional abilities likely to be found in school, pediatric, and other general rehabilitation settings. This approach was also thought to provide secondary benefits for promoting affordability by allowing for manufacturer efficiency during tooling, assembly, and ongoing service.

While the concept of a unified device design appeared appealing to clinicians and special educators, ultimately children with disabilities and their parents needed to feel confident that the device was safe, comfortable, and usable in order for likely adoption. A set of modifications was created and refined over a 2 year development period, including a redesigned seat to ease access for younger children and eliminate the need for a ramp and platform, adjustable pedals to accommodate the shorter legs and bodies of young children, integrated removable ankle-foot orthoses to aid stability for children with profound leg weakness, a modified-crank assembly to accommodate the shorter steps of children as young as 3 years old, and handle modifications to allow shorter/smaller upper extremities to participate in the exercise. The resulting pediatric-modified ICARE was rated significantly more positively by parents, with mean scores across categories ranging from 87.7 to 90.9 on a 100 point VAS as compared to mean scores ranging from 37.5 to 44.3 when children used the unmodified device. Children's VAS scores also increased notably, but changes were not always significant in part because of the small number of children (n = 8) capable of providing data using the VAS. Our challenge obtaining reliable quantifiable data from young children reinforced the importance of seeking input from parents/caregivers during the study. While only 40% of parents indicated a willingness to have their child using the unmodified technology, 93% of parents indicated their child would use the pediatric-modified ICARE if available.

Based on the surveys conducted prior to and during this study, the most critical modifications included: elevating foot pedals (to interact with console and reach grips), modified step length (to address the shorter steps of children), step width adjustment (expected to improve lower extremity weight bearing posture in the frontal plane), and the refined elevating and pivoting seat design (to ease device access and reduce footprint of device when space is constrained). While not essential, the modified pivoting handgrips also allowed younger children with shorter arms to safely use the reciprocally moving handles. Alternatively, children could have used the two sets of stationary handles. An option to using the integrated stirrup design for the pedals would be for children to wear their AFOs; however, the integrated stirrups were of benefit when children with calf weakness forgot to bring their AFOs or if additional frontal plane control of the lower extremity was warranted. However, the system's external harness could be used to provide additional body weight support and reduce sagittal and frontal plane demands if needed.

Despite perceived improvements in safety, comfort, and usability, additional opportunities for device refinement remain. In particular, although narrowing interpedal distance from a fixed position of 10 cm to an adjustable position as narrow as 2.5 cm was perceived as beneficial, a desire for a smaller pedal was expressed. Future designs that allow for integration of inserts to assist with positioning the feet toward the medial borders of the pedals are expected to address this concern. Also of concern was the need to further refine the handles of the pediatric-modified ICARE to allow use by children with smaller/weaker grips. The initial handle modifications brought the handles closer to the child's body but were made from 3.8 cm diameter PVC piping, a diameter that was perceived as too large. Future iterations that allow for a tapering range of hand sizes are expected to be beneficial for addressing the broader needs of the population. Finally, parents and children expressed concern about the comfort of the commercial harness during use of both the unmodified and pediatric-modified ICARE device. In particular, the child's body appeared to slide down in the harness, contributing to a sense of excess pressure in the axillary region and around the neck. Limitations in comfort are a persistent problem across harness designs and warrant future research and development.

Data from the feasibility study provides preliminary evidence that the pediatric-modified ICARE can be used with children as young as 3 years of age who have limited function arising from a wide range of underlying diagnoses. In total, 15 children engaged in 133 sessions and used the prototype device for over 3800 min and more than 162,000 cycles. The typical setup time was less than 5 min for each child, with some able to start in less than 1 min. One child with greater physical and cognitive challenges required ∼10 min for setup. Thirteen children were able to over-ride the motor for brief periods across sessions, highlighting the ability to use different device features with children to address strength and coordination. Despite the capacity to decrease step length to 19 cm (7.5 in) on the prototype device, the shortest self-selected step length used was 25.4 cm (10 in), suggesting that the current range of adjustability is sufficient to meet the needs of young children. Similarly, while the modified device allowed for the pedals to elevate children by as much as 38 cm (15 in; referenced to the original pedal height), the maximum pedal elevation used was only 35 cm (13.8 in), indicating that the current range of pedal height adjustability was adequate to meet the needs of smaller children.

In total, the complete set of prototype modifications cost approximately $8000 and this expense is expected to drop if designs are integrated into production quantities. The motorized modified seat was the most expensive as we elected to use a commercially available seat often integrated into trucks/cars to improve accessibility. In reality, we anticipate that in high production quantities, the manufacturing expense of the final modified seat design would drop notably and would be partially offset by savings arising from not requiring the ramp, platform and existing seat. The second most expensive modification was the crank mechanism, given the need for custom machining in low quantity. Other modifications, including the pedal jacks, modified hand holds, and pedal-integrated AFOs, used relatively inexpensive parts and/or 3D printed components.

While beyond the scope of the current study, future case studies, case series, and randomized clinical trials using the pediatric-modified ICARE would benefit from focusing on homogeneous populations (e.g., prepubescent children with cerebral palsy with prespecified Gross Motor Function Classification System scores or children in the chronic stages of recovering from a traumatic brain injury) and assessing the short- and long-term impact of the intervention on function and cardiorespiratory fitness.

In summary, this work created an affordable prototypic robotic device to address the therapeutic walking and fitness goals of children across a range of ages and body sizes. The work demonstrated the feasibility of using the pediatric-modified ICARE with children as young as 3 years old. Future randomized clinical studies comparing outcomes arising from participation in a pediatric-modified ICARE intervention to those arising from use of traditional therapy approaches should help elucidate the potential for this prototype technology to advance function and fitness in children with disabilities and chronic conditions.

We would like to acknowledge Erin Eckels, Alex Garbin, PT, DPT, Maisie Habron, Noah Keller, Nicole Schwery, and Brett Whorley for their assistance with data collection and processing efforts.

The contents of the manuscript do not necessarily represent the policy of the Department of Education or the Administration for Community Living, and endorsement by the federal government should not be assumed. Additional funding for this work was provided by the Joseph R. and Barbara A. Gard Family Foundation.

  • National Institute on Disability and Rehabilitation Research (H133G130274).

  • National Institute on Disability, Independent Living, and Rehabilitation Research (90IF0060).

Fowler, E. G. , Kolobe, T. H. , Damiano, D. L. , Thorpe, D. E. , Morgan, D. W. , Brunstrom, J. E. , Coster, W. J. , Henderson, R. C. , Pitetti, K. H. , Rimmer, J. H. , Rose, J. , Stevenson, R. D. , Section on Pediatrics Research Summit Participants, and Section on Pediatrics Research Committee Task Force, 2007, “ Promotion of Physical Fitness and Prevention of Secondary Conditions for Children With Cerebral Palsy: Section on Pediatrics Research Summit Proceedings,” Phys. Ther., 87(11), pp. 1495–1510. [CrossRef] [PubMed]
Bandini, L. , Danielson, M. , Esposito, L. E. , Foley, J. T. , Fox, M. H. , Frey, G. C. , Fleming, R. K. , Krahn, G. , Must, A. , Porretta, D. L. , Rodgers, A. B. , Stanish, H. , Urv, T. , Vogel, L. C. , and Humphries, K. , 2015, “ Obesity in Children With Developmental and/or Physical Disabilities,” Disability Health J., 8(3), pp. 309–316. [CrossRef]
Verschuren, O. , Peterson, M. D. , Balemans, A. C. , and Hurvitz, E. A. , 2016, “ Exercise and Physical Activity Recommendations for People With Cerebral Palsy,” Dev. Med. Child Neurol., 58(8), pp. 798–808. [CrossRef] [PubMed]
Fowler, E. G. , Knutson, L. M. , Demuth, S. K. , Siebert, K. L. , Simms, V. D. , Sugi, M. H. , Souza, R. B. , Karim, R. , and Azen, S. P. , and Physical Therapy Clinical Research Network (PTClinResNet), 2010, “ Pediatric Endurance and Limb Strengthening (PEDALS) for Children With Cerebral Palsy Using Stationary Cycling: A Randomized Controlled Trial,” Phys. Ther., 90(3), pp. 367–381. [CrossRef] [PubMed]
Fragala-Pinkham, M. A. , Haley, S. M. , Rabin, J. , and Kharasch, V. S. , 2005, “ A Fitness Program for Children With Disabilities,” Phys. Ther., 85(11), pp. 1182–1200. [PubMed]
Burnfield, J. M. , Shu, Y. , Buster, T. , and Taylor, A. , 2010, “ Similarity of Joint Kinematics and Muscle Demands Between Elliptical Training and Walking: Implications for Practice,” Phys. Ther., 90(2), pp. 289–305. [CrossRef] [PubMed]
Burnfield, J. M. , Irons, S. L. , Buster, T. W. , Taylor, A. P. , Hildner, G. A. , and Shu, Y. , 2014, “ Comparative Analysis of Speed's Impact on Muscle Demands During Partial Body Weight Support Motor-Assisted Elliptical Training,” Gait Posture, 39(1), pp. 314–320. [CrossRef] [PubMed]
Nelson, C. A. , Burnfield, J. M. , Shu, Y. , Buster, T. W. , Taylor, A. , and Graham, A. , 2011, “ Modified Elliptical Machine Motor-Drive Design for Assistive Gait Rehabilitation,” ASME J. Med. Devices, 5(2), p. 021001. [CrossRef]
Irons, S. L. , Brusola, G. A. , Buster, T. W. , and Burnfield, J. M. , 2015, “ Novel Motor-Assisted Elliptical Training Intervention Improves Six-Minute Walk Test and Oxygen Cost for an Individual With Progressive Supranuclear Palsy,” Cardiopulm. Phys. Ther. J., 26(2), pp. 36–41. [CrossRef]
Irons, S. L. , Buster, T. W. , Karkowski-Schelar, E. , Johns, E. , and Burnfield, J. M. , 2016, “ Individuals With Multiple Sclerosis Improved Walking Endurance and Decreased Fatigue Following Motor-Assisted Elliptical Training Intervention,” Arch. Phys. Med. Rehabil., 97(10), p. e34. [CrossRef]
Burnfield, J. M. , Taylor, A. P. , Buster, T. W. , Shu, Y. , Goldman, A. J. , and Nelson, C. A. , 2011, “ Use of Intelligently Controlled Assistive Rehabilitation Elliptical Trainer to Improve Walking and Fitness During Acute Stroke Rehabilitation,” Stroke, 42(3), p. e326. https://www.ahajournals.org/doi/pdf/10.1161/STR.0b013e3182074d9b
Burnfield, J. M. , Yeseta, M. , Buster, T. W. , Taylor, A. P. , and Shu, Y. , 2012, “ Individuals With Physical Limitations Can Benefit From Training on a Motorized Elliptical for Community-Based Exercise,” Med. Sci. Sports Exercise, 45(5S), p. S360. https://journals.lww.com/acsm-msse/Fulltext/2012/05002/Abst_D_FreeCommPosters.5.aspx
Burnfield, J. M. , Shu, Y. , Buster, T. W. , Taylor, A. P. , and Nelson, C. A. , 2011, “ Impact of Elliptical Trainer Ergonomic Modifications on Perceptions of Safety, Comfort, Workout, and Usability for People With Physical Disabilities and Chronic Conditions,” Phys. Ther., 91(11), pp. 1604–1617. [CrossRef] [PubMed]
Beck, R. J. , Andriacchi, T. P. , Kuo, K. N. , Fermier, R. W. , and Galante, J. O. , 1981, “ Changes in the Gait Patterns of Growing Children,” J. Bone Jt. Surg. Am., 63(9), pp. 1452–1457. [CrossRef]
Perry, J. , and Burnfield, J. M. , 2010, Gait Analysis: Normal and Pathological Function, Slack Incorporated, Thorofare, NJ.
Nelson, C. A. , Stolle, C. J. , Burnfield, J. M. , and Buster, T. W. , 2015, “ Modification of the ICARE System for Pediatric Therapy,” ASME J. Med. Devices, 9(4), p. 041010. [CrossRef]
Fryar, C. D. , Gu, Q. , and Ogden, C. L. , 2012, “ Anthropometric Reference Data for Children and Adults: United States, 2007-2010,” Vital Health Stat., Ser., 11(252), pp. 1–48. https://www.cdc.gov/nchs/data/series/sr_11/sr11_252.pdf
Snyder, R. G. , Schneider, L. W. , Owings, C. L. , Reynolds, H. M. , Golomb, D. H. , and Schork, M. A. , 1977, “ Anthropometry of Infants, Children, and Youths to Age 18 for Product Safety Design, Final Report,” Highway Safety Research Institute, The University of Michigan, Ann Arbor, MI, Report Nos. UM-HSRI-77-17 and SAE SP-450.
Winter, D. A. , 2009, Biomechanics and Motor Control of Human Movement, 4th ed., Wiley, Hoboken, NJ.
Contini, R. , 1972, “ Body Segment Parameters—Part II,” Artif. Limbs, 16(1), pp. 1–19. http://www.oandplibrary.org/al/pdf/1972_01_001.pdf [PubMed]
Kadaba, M. P. , Ramakrishnan, H. K. , Wootten, M. E. , Gainey, J. , Gorton, G. , and Cochran, G. V. B. , 1989, “ Repeatability of Kinematic, Kinetic and Electromyographic Data in Normal Adult Gait,” J. Orthop. Res., 7(6), pp. 849–860. [CrossRef] [PubMed]
Kraus, L. , 2017, 2016 Disability Statistics Annual Report, University of New Hampshire, Durham, NH.
Centers for Disease Control and Prevention, 2018, “ Physical Activity Basics: How Much Physical Activity Do You Need?,” Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, Atlanta, GA, accessed Sept. 11, 2018, http://www.cdc.gov/physicalactivity/basics/index.htm
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References

Fowler, E. G. , Kolobe, T. H. , Damiano, D. L. , Thorpe, D. E. , Morgan, D. W. , Brunstrom, J. E. , Coster, W. J. , Henderson, R. C. , Pitetti, K. H. , Rimmer, J. H. , Rose, J. , Stevenson, R. D. , Section on Pediatrics Research Summit Participants, and Section on Pediatrics Research Committee Task Force, 2007, “ Promotion of Physical Fitness and Prevention of Secondary Conditions for Children With Cerebral Palsy: Section on Pediatrics Research Summit Proceedings,” Phys. Ther., 87(11), pp. 1495–1510. [CrossRef] [PubMed]
Bandini, L. , Danielson, M. , Esposito, L. E. , Foley, J. T. , Fox, M. H. , Frey, G. C. , Fleming, R. K. , Krahn, G. , Must, A. , Porretta, D. L. , Rodgers, A. B. , Stanish, H. , Urv, T. , Vogel, L. C. , and Humphries, K. , 2015, “ Obesity in Children With Developmental and/or Physical Disabilities,” Disability Health J., 8(3), pp. 309–316. [CrossRef]
Verschuren, O. , Peterson, M. D. , Balemans, A. C. , and Hurvitz, E. A. , 2016, “ Exercise and Physical Activity Recommendations for People With Cerebral Palsy,” Dev. Med. Child Neurol., 58(8), pp. 798–808. [CrossRef] [PubMed]
Fowler, E. G. , Knutson, L. M. , Demuth, S. K. , Siebert, K. L. , Simms, V. D. , Sugi, M. H. , Souza, R. B. , Karim, R. , and Azen, S. P. , and Physical Therapy Clinical Research Network (PTClinResNet), 2010, “ Pediatric Endurance and Limb Strengthening (PEDALS) for Children With Cerebral Palsy Using Stationary Cycling: A Randomized Controlled Trial,” Phys. Ther., 90(3), pp. 367–381. [CrossRef] [PubMed]
Fragala-Pinkham, M. A. , Haley, S. M. , Rabin, J. , and Kharasch, V. S. , 2005, “ A Fitness Program for Children With Disabilities,” Phys. Ther., 85(11), pp. 1182–1200. [PubMed]
Burnfield, J. M. , Shu, Y. , Buster, T. , and Taylor, A. , 2010, “ Similarity of Joint Kinematics and Muscle Demands Between Elliptical Training and Walking: Implications for Practice,” Phys. Ther., 90(2), pp. 289–305. [CrossRef] [PubMed]
Burnfield, J. M. , Irons, S. L. , Buster, T. W. , Taylor, A. P. , Hildner, G. A. , and Shu, Y. , 2014, “ Comparative Analysis of Speed's Impact on Muscle Demands During Partial Body Weight Support Motor-Assisted Elliptical Training,” Gait Posture, 39(1), pp. 314–320. [CrossRef] [PubMed]
Nelson, C. A. , Burnfield, J. M. , Shu, Y. , Buster, T. W. , Taylor, A. , and Graham, A. , 2011, “ Modified Elliptical Machine Motor-Drive Design for Assistive Gait Rehabilitation,” ASME J. Med. Devices, 5(2), p. 021001. [CrossRef]
Irons, S. L. , Brusola, G. A. , Buster, T. W. , and Burnfield, J. M. , 2015, “ Novel Motor-Assisted Elliptical Training Intervention Improves Six-Minute Walk Test and Oxygen Cost for an Individual With Progressive Supranuclear Palsy,” Cardiopulm. Phys. Ther. J., 26(2), pp. 36–41. [CrossRef]
Irons, S. L. , Buster, T. W. , Karkowski-Schelar, E. , Johns, E. , and Burnfield, J. M. , 2016, “ Individuals With Multiple Sclerosis Improved Walking Endurance and Decreased Fatigue Following Motor-Assisted Elliptical Training Intervention,” Arch. Phys. Med. Rehabil., 97(10), p. e34. [CrossRef]
Burnfield, J. M. , Taylor, A. P. , Buster, T. W. , Shu, Y. , Goldman, A. J. , and Nelson, C. A. , 2011, “ Use of Intelligently Controlled Assistive Rehabilitation Elliptical Trainer to Improve Walking and Fitness During Acute Stroke Rehabilitation,” Stroke, 42(3), p. e326. https://www.ahajournals.org/doi/pdf/10.1161/STR.0b013e3182074d9b
Burnfield, J. M. , Yeseta, M. , Buster, T. W. , Taylor, A. P. , and Shu, Y. , 2012, “ Individuals With Physical Limitations Can Benefit From Training on a Motorized Elliptical for Community-Based Exercise,” Med. Sci. Sports Exercise, 45(5S), p. S360. https://journals.lww.com/acsm-msse/Fulltext/2012/05002/Abst_D_FreeCommPosters.5.aspx
Burnfield, J. M. , Shu, Y. , Buster, T. W. , Taylor, A. P. , and Nelson, C. A. , 2011, “ Impact of Elliptical Trainer Ergonomic Modifications on Perceptions of Safety, Comfort, Workout, and Usability for People With Physical Disabilities and Chronic Conditions,” Phys. Ther., 91(11), pp. 1604–1617. [CrossRef] [PubMed]
Beck, R. J. , Andriacchi, T. P. , Kuo, K. N. , Fermier, R. W. , and Galante, J. O. , 1981, “ Changes in the Gait Patterns of Growing Children,” J. Bone Jt. Surg. Am., 63(9), pp. 1452–1457. [CrossRef]
Perry, J. , and Burnfield, J. M. , 2010, Gait Analysis: Normal and Pathological Function, Slack Incorporated, Thorofare, NJ.
Nelson, C. A. , Stolle, C. J. , Burnfield, J. M. , and Buster, T. W. , 2015, “ Modification of the ICARE System for Pediatric Therapy,” ASME J. Med. Devices, 9(4), p. 041010. [CrossRef]
Fryar, C. D. , Gu, Q. , and Ogden, C. L. , 2012, “ Anthropometric Reference Data for Children and Adults: United States, 2007-2010,” Vital Health Stat., Ser., 11(252), pp. 1–48. https://www.cdc.gov/nchs/data/series/sr_11/sr11_252.pdf
Snyder, R. G. , Schneider, L. W. , Owings, C. L. , Reynolds, H. M. , Golomb, D. H. , and Schork, M. A. , 1977, “ Anthropometry of Infants, Children, and Youths to Age 18 for Product Safety Design, Final Report,” Highway Safety Research Institute, The University of Michigan, Ann Arbor, MI, Report Nos. UM-HSRI-77-17 and SAE SP-450.
Winter, D. A. , 2009, Biomechanics and Motor Control of Human Movement, 4th ed., Wiley, Hoboken, NJ.
Contini, R. , 1972, “ Body Segment Parameters—Part II,” Artif. Limbs, 16(1), pp. 1–19. http://www.oandplibrary.org/al/pdf/1972_01_001.pdf [PubMed]
Kadaba, M. P. , Ramakrishnan, H. K. , Wootten, M. E. , Gainey, J. , Gorton, G. , and Cochran, G. V. B. , 1989, “ Repeatability of Kinematic, Kinetic and Electromyographic Data in Normal Adult Gait,” J. Orthop. Res., 7(6), pp. 849–860. [CrossRef] [PubMed]
Kraus, L. , 2017, 2016 Disability Statistics Annual Report, University of New Hampshire, Durham, NH.
Centers for Disease Control and Prevention, 2018, “ Physical Activity Basics: How Much Physical Activity Do You Need?,” Division of Nutrition, Physical Activity, and Obesity, National Center for Chronic Disease Prevention and Health Promotion, Atlanta, GA, accessed Sept. 11, 2018, http://www.cdc.gov/physicalactivity/basics/index.htm

Figures

Grahic Jump Location
Fig. 1

ICARE technology used to address walking and fitness goals of adults and adolescents with physical disabilities and chronic conditions

Grahic Jump Location
Fig. 2

Bruno Valet® Plus installed on the pediatric-modified ICARE. The white arrows demonstrate the motion of the motorized chair as it elevates from the lowest position (a), retracts over the base of the ICARE (b), and pivots to align the child facing forward (c–e).

Grahic Jump Location
Fig. 3

Screw-driven pedal jack

Grahic Jump Location
Fig. 4

Movement profile of markers placed on posterior and anterior surface of right pedal demonstrated notable similarities when pedal was elevated 33 cm (17 in) on the screw-driven pedal mount (upper trajectories) compared to the traditional ICARE pedal mount (lower trajectories). These data suggest that the screw-driven pedal mount could provide a suitable means of elevating a young child to the console without disrupting pedal trajectory.

Grahic Jump Location
Fig. 5

Adjustable rear crank mechanism accommodated the shorter step length and height requirements of younger/smaller children

Grahic Jump Location
Fig. 6

Pediatric-modified ICARE pedal mounting interface with width adjustable slots

Grahic Jump Location
Fig. 7

Pedal-integrated ankle-foot orthosis in translational dovetail channel allowed customization of external support for each lower extremity during use

Grahic Jump Location
Fig. 8

Removable adjustable handles made it easier for young children with shorter arms to reach and use the reciprocally moving handles without leaning forward or stretching upward. Handles rotated inward and outward to accommodate variations in upper extremity range of motion.

Grahic Jump Location
Fig. 9

Tablet and mounting system on pediatric-modified ICARE

Grahic Jump Location
Fig. 10

Example of challenges a young child might experience when trying to use the ICARE (a) and pediatric-modified ICARE (b)

Tables

Table Grahic Jump Location
Table 1 Anticipated barriers and possible solutions for ICARE use by 3–12 year old children
Table Grahic Jump Location
Table 2 Baseline characteristics of children who participated in assessment of the pediatric-modified ICARE
Table Footer NoteNote: GMFCS—Gross Motor Function Classification System, M—male, F—female, B—bilateral, and L—left.
Table Grahic Jump Location
Table 3 Visual analog scale scores (n = 15 parents and n = 8 children with disabilities) rating perceptions of safety, comfort, and usability of the adult ICARE and pediatric-modified ICARE. Scores are mean (standard deviation) [range] and the 95% confidence interval (CI, in italics) around the mean and for the difference of means. Upper limit CI truncated at a maximum of 100.
Table Footer NoteaZ-score from Wilcoxon signed rank test due to data set failing to achieve normality.
Table Grahic Jump Location
Table 4 Age, number of sessions, total time using device, total time spent over-riding the motor's assistance, step length, pedal height, and number of strides completed for children (n = 15) who participated in a study of the feasibility of using the pediatric-modified ICARE
Table Footer NoteNote: NA—not available.

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