Child development is situated within movement, exploration, and interaction with objects, people, and the world.1 Self-directed mobility is defined as mobility that is controlled by an individual and may include (a) ambulation, such as walking, (b) use of nonpowered technology, such as prosthetics, walking aids, and manual wheelchairs, or (c) use of powered technology, including motorized wheelchairs, battery-operated ride-on toy cars, or other similar device.2 Self-directed mobility in the form of independent walking is associated with children's psychological development, particularly in spatial, cognitive, emotional, and social understanding.3–5 Children with mobility-related disabilities often experience delays across developmental domains.6–9 One disability that is associated with delays in independent walking is Down syndrome.
Down syndrome is a genetic disorder that affects 1 in 700 infants in the United States each year.10 Infants with Down syndrome very often experience delays in the acquisition of motor skills including rolling, sitting, crawling, pulling from sit-to-stand, and standing with assistance.11 , 12 Infants developing typically demonstrate independent walking between 10 and 14 months of age. In comparison, infants with Down syndrome often demonstrate independent walking around 24 months of age or later.13 Body weight-supported treadmill training is a feasible and effective tool for advancing the specific outcome of independent walking.14–17 Outside of their treadmill training, infants who are not independently walking need technology and training to provide the hours of self-directed mobility enjoyed by their peers. An emerging option for targeting physical skills while simultaneously providing self-directed mobility includes modifying off-the-shelf, battery-operated ride-on cars.
Commercially available ride-on cars are electrically and mechanically modified using readily available materials. For example, installing a large, easy-to-press switch allows easy activation using limb or head movement. Common materials used to build a customized seating system include PVC (polyvinyl chloride) pipe, swimming kickboards, and Velcro.18 Previous case reports and group studies suggest that modified ride-on cars are a feasible option for young children with disabilities to use for self-directed mobility, socialization, enjoyment, and play.19–23 Previous research includes a case report of an infant with Down syndrome who also demonstrated advances in mobility, self-care, and social skills.23
Traditionally, modified ride-on cars are used while seated. A recent innovation is the sit-to-stand version of the modified ride-on car.21 The sit-to-stand version includes both a seated mode and a standing mode where children are required to pull themselves from sit-to-stand to activate the modified ride-on car. One study provided a sit-to-stand modified ride-on car to a child with a disability.21 That child increased his peer interaction by 10% when using his modified ride-on car within an early education setting as compared with using forearm crutches.21 One potential advantage of the sit-to-stand version is the different experience it affords in relation to perception-action coupling, especially with experiences of optic flow and improved visual proprioception.
Visual proprioception is an optically induced sense of self-movement created by patterns of optic flow in the environment.24 Optic flow refers to changes in patterns of apparent motion in one's visual scene caused by the relative motion between the observer and the environment.24 Visual proprioception is tightly woven with postural control, as visual proprioception allows one to maintain and correct posture with respect to the direction of self-movement.5 While seated modified ride-on cars provide an experience of optic flow, they do not link motor behavior with sensory experience (ie, the child is not in a standing position, activating leg muscles, maintaining balance, etc). Another advantage of the sit-to-stand modified ride-on car is the “just right” challenge it affords compared with the seated version. A “just right” challenge is provided through the increase in postural and cognitive requirements, as a child transitions between the seated and sit-to-stand versions. While using the seated mode, the postural requirements are constrained to assisted and independent sitting, while the cognitive requirement is to press a switch for car activation, which is intuitive based on typical cause-and-effect toys provided to young children. The sit-to-stand version encourages more complex postural requirements, including the ability to pull from sit-to-stand and maintain balance while in an upright posture. The cognitive requirement is also more advanced because children must learn a different, and less intuitive physical skill, pulling from sit-to-stand to activate the car, rather than reaching with their hand to press the switch.
The current study extends previous reports of children with disabilities using modified ride-on cars for mobility21–23 in 2 ways. First, this study provided a 9-month modified ride-on car intervention as compared with 3 months, the longest previously reported duration. Nine months was chosen as an intervention length to capture the transition between use of standing and seated modes, which may be variable for infants with Down syndrome. Also, 9 months is a similar duration of the treadmill training studies implemented with infants with Down syndrome. Second, this study provided the sit-to-stand version of the modified ride-on car that encouraged practice of physical skills such as pulling from sit-to-stand, bearing weight during assisted standing, and balance, as well as self-directed mobility. Infants with Down syndrome are rarely considered for powered mobility devices due to the expectation that they will achieve independent walking, in the absence of comorbidities or other medical conditions. There are currently no commercially available powered mobility devices for children younger than 3 years. This leaves a gap during which children with Down syndrome are unable to learn, explore, play, and develop through independently moving around their environment. Previous modified ride-on car research with seated modes only has demonstrated that interventions are feasible, and that children learn to press the activation switch, and enjoy driving.19 , 22 , 23 However, these findings have not been replicated with modified ride-on cars that include a standing mode provided to infants with Down syndrome.
Due to the intellectual disability associated with Down syndrome, it is unknown whether, and how quickly, children switch from the seated to standing driving modes. The purpose of this case series, descriptive study was to determine the feasibility of families and infants with Down syndrome to use a modified ride-on car with seated and standing modes. This study will determine whether or not the modified ride-on car intervention warrants further testing.25 Feasibility will be determined through 3 specific aims that align with appropriate areas of feasibility studies25:
- To determine the practicality of a home-based, 9-month intervention that provides modified ride-on cars with seated and standing modes. Practicality is defined as “... the extent to which an intervention can be delivered when resources, time, commitment, or some combination thereof are constrained in some way.”25 See the Methods section for details. Based on previous research,23 we hypothesize that families will demonstrate a variety of adherence rates and use the modified ride-on car in a variety of locations while engaged in different types of activities.
- To determine the ability of infants to implement the intervention as measured by independent activation while using the modified ride-on car in seated and standing modes. Implementation includes the extent “... an intervention can be fully implemented as planned or proposed, often in an uncontrolled design.”25 See the Methods section for details. Based on previous research,19–23 we hypothesize that all infants will learn how to independently activate the modified ride-on car in seated and standing modes.
- To determine the acceptability of the intervention as measured by level of enjoyment demonstrated by infants when using the modified ride-on car while in seated and standing modes. Acceptability is defined as how the recipients react to the intervention.25 See the Methods section for details. Based on previous research,19 , 20 , 22 , 23 we hypothesize that infants will demonstrate enjoyment as measured through facial expressions via behavioral coding and parent report via the fun index.
Participants included 4 infants with Down syndrome (1 female). The infants began the study at ages (months:days) 7:12, 7:19, 9:7 (months:days); adjusted age 8:20 for prematurity, and 7:19. At the start of the study, each child had the ability to sit supported with minimal assistance, but was not sitting independently. All infants were diagnosed with trisomy 21, based on parent report. All infants received services through their local early intervention programs, with an average of less than 2 physical therapy visits per month. Approval from the university's Institutional Review Board and written parent/guardian consent was obtained prior to data collection.
Description of the Modified Ride-On Car
Each infant used a ride-on car that was modified to have a seated mode (Figure 1A) and a standing mode (Figure 1B). The seated drive mode was activated using a small, custom-built, easy-to-press hand switch on the handlebars. A small activation switch was installed under the seat so that activation of the modified ride-on car required the children to pull themselves into standing and remain standing to make the car drive. See previously published technical reports for more details on general modifications.18 , 26 (Modification to off-the-shelf ride-on cars is an unlabeled use of a commercial product.)
Description of Intervention
As in previous case reports,2 , 19 , 22 , 23 the intervention included education and training components. During the initial home visit, the researcher provided education on safe use of the modified ride-on car, including how to position the child in the car, how the switches work, how to switch between driving modes, and how to charge the battery. The family kept the modified ride-on car at their home and was requested to give their child the opportunity to drive 8 minutes per day, 5 days per week.
The intervention had 2 phases, the first when the child drove the car using the activation switch on the handlebars while seated (seated phase), and the second phase when the child was required to pull to stand to activate the car (standing phase). The transition to the standing phase was determined individually for each child based on the ability to pull to stand with no more than minimal assistance (<25% assistance as graded by the family and/or researcher) and maintain supported standing for approximately 3 seconds.
As in previous case reports,2 , 22 , 23 researchers visited each infant twice per month. At each visit, a 10-minute video recording of the child driving the modified ride-on car was made for behavior coding. Each visit included time for the researcher and the family to discuss the infant's driving experiences and problem solve to create new and interesting activities to maintain the child's interest and “just right challenge.”
Data were collected for child A for 17 visits, child B for 16 visits, child C for 17 visits, and child D for 18 visits. The number of visits varied due to cancellations or scheduling conflicts during the intervention.
Activity Logs and Fun Index. As in previous case reports,2 , 19 , 23 the daily activity log included parent reports of the days and minutes of driving time, a “fun index” score, location, and general activities such as open exploration or playing with a sibling. An adherence rate was calculated based on the number of days infants drove for at least 8 minutes across 180 days, based on the 5 days per week recommended use during the 9-month intervention. The fun index was an ordinal scale that captured the family's perception of the child's enjoyment during daily driving sessions. Parents scored each session from 1 to 10, with a 10 indicating the highest level of fun.
Video Coding. Data coding was completed for each 10-minute video recording to analyze the child's mobility and facial expressions in the modified ride-on car. Three coders were trained on coding procedures with practice video recordings. This allowed for discussion of disagreements and clarification of key behaviors. Interrater and intrarater observer agreement (IOA: >85%) was established using the ratio of agreements/(agreements + disagreements) × 100 to establish a percentage of agreement. The more than 85% criterion of IOA was determined a priori. All 3 coders demonstrated an IOA of more than 85% for 10% of videos for each child prior to formal data coding (IOA range: 86%-94%) and halfway through coding (IOA: 100% for all coders) to ensure that coders had not drifted in how they coded observations. Because all coders demonstrated 100% IOA halfway through coding, further IOA was not established.
Mobility. Mobility was defined as time that the modified ride-on car was moving for intervals of at least 5 seconds. Percent driving time and total time driving (minutes and seconds) of each 10-minute video were recorded for the following driving categories:
- Independent mobility. The child drives after independently activating the switch without adult assistance.
- Assisted mobility. The child drives the car following an assisted switch contact. The child is given assistance to activate the switch and then the adult removes their hand and the child is able to drive without additional help.
- Caregiver mobility. The child drives after an assisted switch contact and someone holds the child's hand on the switch or helps for child to remain standing.
Facial Expressions. Facial expressions were recorded using frequency counts. Positive and negative facial expressions were tallied for each video recording. A 3-second period of neutral facial expression was observed between discrete counts of facial expressions. The percentage of positive and negative facial expressions will be calculated using a ratio of the expression type (positive or negative) to the total number of expressions observed in each video.
Determination of Aims
Aim 1. Practicality was determined by each family's adherence rate to the recommended 8 minutes of driving per day, at least 5 times per week while using the modified ride-on car throughout the intervention. The 8 minutes of driving per day was based on the dosage of treadmill training studies with infants with Down syndrome.16 Practicality was determined successful by a minimum of 50% adherence rate. Training time, location of driving, and general activities were recorded.
Aim 2. Implementation was determined successful if independent activation of the modified ride-on car was demonstrated for a majority of the time (>50%) for a majority of driving sessions (>50%).
Aim 3. Acceptability was determined successful if a majority of facial expressions observed (>50%) were positive for a majority of driving sessions (>50%) as measured via behavioral coding. Acceptability was also determined as successful if parents perceived their child's enjoyment as an average of at least 5.0 as measured by the fun index.
Description of Outcomes
Activity Logs and Fun Index. The following results do not include the days and minutes infants drove during researcher-led driving sessions throughout the study.
Only 1 child demonstrated an adherence rate of greater than 50% throughout the intervention (child A: 43%; child B: 2%; child C: 64%; and child D: 22%). See the Table for mean, standard deviation, and range of driving time per session and total driving.
- Child A: The primary driving location was the kitchen, living room, and hallway or outside in the cul-de-sac adjacent to their home. The primary driving activity was open exploration, and at times chasing his older brother. Parents frequently reported smiles and vocalizations when in the ride-on car.
- Child B: The primary driving location was in the open space of their home with the activity being open exploration. No detailed information was provided by the family.
- Child C: The primary driving location was outside their home on the sidewalk with occasional uses in the community such as at church or the park. The primary activity was open exploration and social interaction with his older brother and neighbors. Parents noted increased engagement during shorter driving sessions.
- Child D: The primary driving locations were around kitchen and living room and in the family's driveway. Parents noted that she was motivated to drive when given a drink of water as a goal to move toward.
All of the parents reported an average fun index of over 5.0 for their child throughout the intervention. See the Table for mean, standard deviation, and range of fun index scores.
Mobility. During the first few visits, each participant engaged in either a small amount of driving or required assistance from an adult to drive. Three out of the 4 infants became accustomed to the novelty of using the modified ride-on car and often displayed independent mobility as the primary form of driving within the first 4 to 8 intervention visits. Independent mobility was determined by the occurrence of 2 consecutive driving sessions (Figure 2). When transitioning to the standing driving mode, an increase in caregiver and assisted driving was initially noted. Families reported that the transition to the standing driving mode was a dynamic process where they would provide their child a driving opportunity that included some seated mode use and some standing mode use in the same driving session. However, detailed notes were not provided in the activity logs to describe the transition process more in-depth. Throughout the intervention, with 1 exception (Child B), infants demonstrated independent activation of the modified ride-on car for a majority of the time (>50%) for a majority (>50%) of driving sessions (Table).
Facial Expressions. All of the infants demonstrated a majority of positive facial expressions (>50%) for a majority of driving sessions (>50%) when using the modified ride-on car in the seated mode, the standing mode, and throughout the intervention (Table and Figure 3).
Specific aim 1 was to determine the practicality of a home-based, 9-month intervention that provides modified ride-on cars with seated and standing modes. Our hypothesis that there would be a variable amount of adherence to the recommended 8 minutes/day at least 5 days/week driving regime was upheld (2%-64%). One explanation for low adherence rates includes parent-reported barriers to providing their child with opportunities to use the modified ride-on car such as finding appropriate spaces to drive, inclement weather, and difficulty finding time based on other commitments. Families also reported their own decreased motivation to provide opportunities for their child to drive once competence in switch activation was demonstrated. This is an interesting but unexpected finding. Families serve as the gatekeepers to provide their children with opportunities to use a modified ride-on car. It is equally, if not more important, to ensure that families also perceive a “just right” challenge for their child in using a modified ride-on car. In future studies, adherence may be encouraged through providing a more comprehensive guide to families that outlines specific activities and games that involve different levels of difficulty and complexity. This would provide families with opportunities to provide a “just right” challenge, as their child gains experience and skill with using a modified ride-on car. Another potential explanation for the decreased adherence of the current study compared with other modified ride-on car studies may be the 9-month intervention period.2 , 19 , 23 It may be easier for families to provide consistent opportunities for their child to use a modified ride-on car during shorter periods, such as previously reported 3-month interventions.2 , 19 , 23 For example, in a previous case series2 involving modified ride-on cars, the reported adherence rates for 2 of the 3 children were 100% and 67% (none of the children in the current study reached 67%). It should be noted that the third child in the previous case series demonstrated a 10% adherence rate and suggests that considerable variability exists between families in providing their child opportunities to use a modified ride-on car, regardless of intervention length.
We encouraged families to collaborate with their child's physical therapist to support use of the modified ride-on car through developing strategies and activities to encourage a “just right” challenge. However, the physical therapists of the infants enrolled in the study were not systematically included in the study. Our future work will include a more purposeful integration of families, physical therapists, other pediatric clinicians, and researchers to better support families throughout the intervention.
Specific aim 2 was to determine the ability of infants to implement the intervention as measured by independent activation while using the modified ride-on car in seated and standing modes. Our hypothesis was upheld as most infants demonstrated an ability to drive independently in each mode. With 1 exception (child B), infants were able to drive independently the majority of the time within 4 to 8 visits, demonstrating their learning of how to operate the modified ride-on car. A likely explanation for this exception is that child B had the fewest opportunities to drive the modified ride-on car at home to gain the skill of independent driving. Child B demonstrated a steeper learning curve, taking 6 researcher visits (2 of the first 8 had to be cancelled by the family) before driving at all during the video recording session, and not until visit 13 did child B independently drive greater than 10% of the recorded time. Our results suggest that infants with Down syndrome do not have difficulty learning to drive the car or switching driving modes, thus providing the opportunity for modified ride-on cars to be used as a mobility intervention. A remaining question is whether or not children with Down syndrome will use a modified ride-on car for mobility to explore and play with peers when driving is embedded within a social peer environment, such as an early childcare center. As previously reported in a preschooler with cerebral palsy who was nonmobile and provided access to a powered mobility device, he did not automatically use his new mobility for play with peers.27 Yet, research indicates that young children use their mobility for social play from a young age.28 A potential direction for future research is to provide mobility interventions for children with disabilities in natural settings with peers to determine how mobility may be used for play with peers.
Specific aim 3 was to determine the acceptability of the intervention as measured by level of enjoyment demonstrated by infants when using the modified ride-on car while in the seated mode, the standing mode, and throughout the intervention. Our hypothesis that infants will enjoy driving the modified ride-on cars was supported as evidenced by mostly positive facial expressions. For 3 of the 4 infants, parents reported high average fun indexes, over 7, indicating enjoyment during driving opportunities. It is clear that infants in the current study enjoyed using the modified ride-on car. This result is promising because it suggests that infants with Down syndrome did not experience prolonged frustration when transitioning between the seated and standing modes.
Several observations led to promising possibilities for the practical and clinical implications of using a modified ride-on car in seated and standing modes for children with disabilities. First, each infant's family reported that the child practiced pulling to stand and supported standing with a higher frequency and with less need for assistance when using the modified ride-on car, and they felt as though their child was more motivated to do so because they enjoyed driving their modified ride-on car. The motivation of the infants, the physical practice of motor skills, combined with the benefits of self-directed mobility, suggests an intervention with multiple benefits. Second, 3 of the 4 infants in this study used the modified ride-on car to engage in goal-directed mobility, such as standing up to make the car go toward a toy. Third, the modified ride-on car in seated and standing modes could also be used as a complementary intervention with treadmill training. Treadmill training would provide practice of partial weight bearing and stepping while the modified ride-on car would provide the practice of pulling to stand and standing as well as self-directed mobility. In combination, these interventions may give a child task component practice as well as the developmental benefits associated with self-directed mobility.3 , 5
There were limitations of the current study. Due to the descriptive design of the study, it is not possible to generalize results, nor attribute causality to the intervention. The present study did not include a baseline prior to the intervention. Furthermore, this study did not control for the possible effect of maturation and growth on the performance of infants. The variable amounts of driving for each participant also limit the ability to draw generalizable conclusions. This study demonstrated that an intervention with modified ride-on cars that include the seating and standing modes is feasible for infants with Down syndrome and provides opportunities for future research.
Future studies warrant additional exploration of the use of modified ride-on cars to provide opportunities for self-directed mobility and the practice of physical skills, such as pulling to stand and assisted standing for infants with disabilities. This may include an objective outcome measure to determine the effect of sit-to-stand modified ride-on car use on infants' development. Similar to treadmill training interventions, the sit-to-stand version of the modified ride-on car may lead to an earlier onset of independent walking, resulting in developmental benefits for children. A more detailed examination of how infants transitioned from use of the seated mode to the standing mode would provide valuable information to clinicians. This information may inform the development and testing of effective behavioral strategies that clinicians may employ to facilitate infants to transition from the seated to standing modes. Future studies could address the limitations of the current study by the use of single-subject research designs that include multiple participants and phases (such an ABA design) and the inclusion of other disabilities that impact mobility and development in young children to allow for better generalization of the results. Further investigation on the factors that influenced adherence for each family would inform researchers and clinicians on how best to provide support and facilitate the use of modified ride-on cars for children with disabilities.
WHAT THIS CASE ADDS TO EVIDENCE-BASED PRACTICE
This study demonstrated that an intervention with modified ride-on cars that include seating and standing modes is feasible for infants with Down syndrome.
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