DME

Blog posts of '2020' 'May'

Functional Elements of the Explorer Mini's Saddle Seat


Part 11 in our series about developmental milestones in early childhood focusing on mobility. 


The saddle seat was designed intentionally to facilitate an upright posture through developmentally appropriate supports. Research regarding the use of either flat seats or saddle-like seating has been conducted over the years. The work of DT Reid (1996) tells us that children with Cerebral Palsy displayed better seat alignment and postural control of the upper body resulting in a more efficient reaching path in a saddle seat making it easier to reach desired item. In 2006, Stavness reviewed the literature on the effect of positioning for children with cerebral palsy and upper extremity function. Evidence supports that an upright position, versus sitting back in a chair, improves reaching and hand manipulation. Additionally, the optimal position is a cutout tray, a sloped seat forward of 0-15 degrees and that the line of gravity be in front of the “sit bones”, otherwise known as the ischial tuberosities.

Recommendations for Seating

Sunny Hill Health Centre for Children provide very specific parameters of optimal seating for children with Cerebral Palsy (CP) based on extensive research. Their aim in creating these recommendations was to develop symmetry of the pelvis, trunk, neck and head in all positions. They suggest:

  • Change positions to encourage motor development and movement
  • Introduce sitting at around 5 months gradually bringing them into a more upright posture to encourage head control
  • If needed provide lateral supports and a thigh guide to encourage hip abduction and external rotation and aligned foot position
  • Aim for hip abduction of 15-30 degrees and external rotation of 5-15 degrees.

The shape of the saddle seat is designed to provide this hip abduction and external rotation while weight bearing through the feet. While it is not essential that your young child always be in this position, it is optimal for hip bone growth and development. For children who are not crawling or walking this helps develop the hip joint and head of the femur (thigh bone). The weight bearing in this position helps build a cup like structure around the hip joint for stability.

These recommendations are not just for children with CP, they are developmentally aligned for all children with mobility impairments. 

Incorporating the research findings regarding the development of young child sitting skills, the Explorer Mini saddle seat is designed to optimize weight bearing on the ITs by not including padded seating. The Explorer Mini is not designed for children to use continuously, therefore padding is not necessary. As always, each child is different and skin care checks should be routine when altering a young child’s position.

You may wonder why the seat does not offer a seat belt. The seat and tray table as well as the foot support are designed to allow for dynamic movement. If movement is not encouraged the muscle fibers and nerve endings become static and do not communicate the messages of movement to the brain. By placing a seat belt on the device, we would restrict movement and not facilitate an upright posture. If your child cannot sit upright at first, do not give up.

Work with the therapist to find the best seat height to encourage this level of support. Remember your child is learning. When a child is learning to crawl, we let them struggle and fail before they finally achieve the skill. The same is true for upright sitting in the Explorer Mini. They may not be instantly successfully. But be assured we have worked with great intention to know how to assist in development of posture, environmental exploration and movement.

What is Success? 

The picture below show Davis when he was originally put in the device. Initially he was not putting weight through the seat and his abnormal reflexes had him leaning to one side.

The temptation was to go and straighten him out, provide supports to keep him upright. But we didn’t do that. Davis struggled and worked at getting his trunk more upright and saw the joystick that he wanted to reach. Over time during this session of 1 hour, Davis was successful at bringing his body to a more upright position. Is this position perfect? No, but neither was that first crawl attempt of a child without mobility impairments!

The Explorer Mini is a tool that can be used over time to allow very young children to get into developmentally appropriate positions to achieve a more upright posture, and as a result promote visual, sensory, and motor integration, and provide the opportunity for independent mobility. Success in the Explorer Mini may initially be measured by showing small gains or improvements in ability to maintain midline positioning for longer periods of time while visually locating or reaching for the joystick to help promote development of postural control, strength, and endurance required for self-initiated mobility. 


Reid, D. T. (1996). The effects of the saddle seat on seated postural control and upper-extremity movement in children with cerebral palsy. Developmental Medicine and Child Neurology, 38, 805–815.

Stavness, C., (2006). The effect of positioning for children with Cerebral Palsy on upper-extremity function: A review of the evidence. PT and OT in Pediatrics, 26,39-52

Sunny Hills Health Centre for Children. (2014). Positioning for children with GMFCS Levels IV-V: Focus on Hip Health. Retrieved from sunny-hill-clinical-tool-for-hip-health-gmfcs-iv-v-2014.pdf 


Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS
Associate Professor in the School of Occupational Therapy at Belmont University

Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS is an Associate Professor in the School of Occupational Therapy at Belmont University in Nashville, TN. She has over 40 yrs of OT experience and 20 in the area of Assistive Technology. She is a member of the International Society of Wheelchair  Providers, and the Clinicians Task Force. She is a reviewer for American Journal of OT and guest reviewer for many other journals. She has presented internationally, nationally and regionally particularly in the area of pediatric power mobility. She has authored journal articles and textbook chapters in the area of OT and pediatric mobility and access.

Conventions of Functional Seating in the Explorer Mini   


Part 10 in our series about developmental milestones in early childhood focusing on mobility.


We can find all sorts of ways to sit, usually not always the most optimal but we change our positions based on the task we are performing. Reading a book, maybe our legs are propped on the couch, or we sit cross legged. If engaged in writing or typing we are probably resting our feet on the floor, leaning slightly forward and resting our hands on the desk or chair supports. A young child with delayed milestones or mobility impairments cannot access those alternative positions. They are dominated by gravity. If they have not had opportunities to meet the developmental milestones in incremental order, their posture will be affected, therefore the task they perform will be altered.

If you think about how a young child develops trunk and head control, it’s logical to think about ways to correct that. If the child is unable to do so themselves, they will need postural support. In order for a young child to begin using their arms and hands they need first to control their core muscles. This is why a pre-crawling infant will spend a lot of time rocking back and forth when on all fours. This movement around the joint strengthens the joint capsule—where the muscles attach—to help build muscle strength and endurance.  

How does the Explorer Mini provide functional seating? 

The Explorer Mini is designed for the non-ambulatory and the emerging ambulator. It provides the developmentally appropriate supports to establish an upright trunk. We call this sequence of movements and postures the “conventions of functional seating”. In this case function means whatever that young child would be doing at that stage of their development.  

The elements of functional seating: One must have a stable base of support on the buttocks and thighs. In order to prevent a slumping posture, the pelvis needs to be tilted forward. 

When we typically visualize a child with mobility impairments in “functional seating”, we think of them in a wheelchair with a cushion, back support, head support, and maybe even lateral trunk supports. It’s easy to assume that all these supports are required to provide stability for function. This may be true, but the supports don’t encourage the strengthening of core muscles or activation of the trunk muscles for posture, head control, and ultimately functional use of the hands.

There is now an option with the Explorer Mini to put young children in a posture of functional seating that will place the pelvis in a forward position for stability, with feet directly underneath. The forearms provide added stability by weightbearing on the tray, triggering the trunk muscles to activate and extend, which encourages an upright head. By allowing freedom of movement through intentionally not using straps or belts, young children can safely work to bring themselves into a functional seating posture. Although the Explorer Mini is not intended for full time use, it is a device that can be used intermittently and help a very young child develop a functional upright posture, with the reward being intentional, self-initiated movement to explore their environment. 


 

Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS
Associate Professor in the School of Occupational Therapy at Belmont University

Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS is an Associate Professor in the School of Occupational Therapy at Belmont University in Nashville, TN. She has over 40 yrs of OT experience and 20 in the area of Assistive Technology. She is a member of the International Society of Wheelchair  Providers, and the Clinicians Task Force. She is a reviewer for American Journal of OT and guest reviewer for many other journals. She has presented internationally, nationally and regionally particularly in the area of pediatric power mobility. She has authored journal articles and textbook chapters in the area of OT and pediatric mobility and access.

 

 

The Importance of the Explorer Mini's Midline Joystick for Development


Part 9 in our series about developmental milestones in early childhood focusing on mobility. Read our previous blog entries below.


Upper extremity function, such as reaching, grasping, and manipulating objects requires dynamic stability of the shoulder girdle on a stable trunk. The Explorer Mini tray provides this support to the upper extremities to allow for midline access to the joystick. The design of the midline joystick allows for the two hands to come together to support hand manipulation which contributes to handedness and haptic perception development. 

What is Handedness Development?

Handedness or hand dominance typically occurs in children between the ages of 2-3 years of age. For children who are immobile and use a power mobility device with a joystick, hand dominance may be affected by the joystick placement to the right or to the left. Having a joystick in midline encourages bimanual exploration and allows hand dominance to be determined naturally. Additionally, having a joystick placement on the right or left may lead to scoliosis because the trunk may be hypotonic while the extremities may be hypertonic for example for children with cerebral palsy. 

 

What is Haptic Perception?

Haptic perception is the recognition of objects and object properties by the hand without the use of vision. The hands and mouth are the primary sources of haptic information for an infant. “As the infant develops, the hands become a perceptual system that increasingly participates in the infant’s construction of knowledge” (2). Infants will first learn about their environment through haptic perception and as mobility develops their ability to interact with their environment allows for greater exploration. 

“Vision appears to guide the development of haptic manipulation strategies. It is not until later in life that vision and somatosensory sensations appear to take on separate but supportive roles in object identification and use" (2). For this reason, it is a strategic part of development that the young child may “play” with the joystick, manipulating it, feeling the texture and even mouthing the joystick. Once he has an opportunity to develop the haptic perception and realize that what he is seeing is the same as what he is feeling, he may then come to realize that the joystick actually moves the device. Therefore, as part of training and exploration it is essential that the young child have adequate opportunities to explore the Explorer Mini before understanding that movement is part of the package. 

How does posture affect upper extremity function?

Evidence supports that an upright posture versus a reclined posture improves upper extremity function such as reaching and manipulation (5). The posture that a child is put in with the design of the Explorer Mini is a forward posture, using weight bearing of the upper extremities. 


1.Hagert, E., Persson, J., Werner, M., & Ljung, B-O. (2009). Evidence of wrist proprioceptive reflexes elicited after stimulation of the scapholunate interosseous ligament. American Society for Surgery of the Hand, 34A. 642-651. 

2.Henderson, A., & Pehoski, C., (2006). Hand Functions in the Child: Foundations for Remediation, 2nd edition. Mosby, Elsevier. St. Louis, Missouri.

3.Michelson, JD, & Hutchins, C., (1995), Mechanoreceptors in human ankle ligaments. The Journal of Bone and Joint Surgery. British vol. 77-B

4.Rosenblum, S., & Josman, N. (2003). The relationship between postural control and fine  manual dexterity. Physical and Occupational Therapy in Pediatrics, 23,(4). 47-60. 

5.Stavness, C., (2006). The effect of positioning for children with Cerebral Palsy on upper-extremity function: A review of the evidence. PT and OT in Pediatrics, 26,39-52 

6.Westcott, S., & Burtner, P. (2004). Postural control in children: Implications for pediatric practice. PT and OT in Pediatrics, 24, 5-55. 

7.Scheiman, M. (2011). Understanding and managing vision deficits: A guide for occupational therapists. Thorofare, NJ: SLACK Incorporated.  


 

P, CEAS, CAPS
Associate Professor in the School of Occupational Therapy at Belmont University

Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS is an Associate Professor in the School of Occupational Therapy at Belmont University in Nashville, TN. She has over 40 yrs of OT experience and 20 in the area of Assistive Technology. She is a member of the International Society of Wheelchair  Providers, and the Clinicians Task Force. She is a reviewer for American Journal of OT and guest reviewer for many other journals. She has presented internationally, nationally and regionally particularly in the area of pediatric power mobility. She has authored journal articles and textbook chapters in the area of OT and pediatric mobility and access.

 

Could your child benefit from the Explorer Mini ? - Part 2

 


Part 8 in our series about developmental milestones in early childhood focusing on mobility. Read our previous blog entries below.


 

Functional Groups Examples
Children who may never ambulate
  • Children with severe cerebral palsy, spinal muscle atrophy types I and II.
Children with inefficient mobility
  • Those who ambulate but are unable to do so at a reasonable rate of speed or with acceptable endurance.
  • This includes children with milder forms of cerebral palsy and myelomeningocele with upper extremity involvement.
Children who lose the ability to walk or to walk efficiently
  • Children with progressive neuromuscular disorders.
  • Children who experienced a traumatic brain or spinal event.
  • Developmental delay of this group would depend upon when their mobility and structures impaired.
Children who need mobility assistance in early childhood
  • Often progress to independent mobility with age
  • Children with conditions such as osteogenesis imperfecta and arthrogryposis
  • Considerations for this group are both developmental and functional

  


There are hundreds of pediatric medical diagnoses that may warrant the consideration of a power mobility device (PMD). However, there are some limitations of associating the use of a device solely with a specific diagnosis. One consideration is that many children are not diagnosed with a medical diagnosis as no etiology can be pinpointed for the cause of the deficits. In this common situation, a child may demonstrate delays in development but there is no known cause. In these cases, it is not unusual to wait until a child is 24-48 months to deem that this is a delay in development. And we know from our previous blog what happens when a child is unable to perform self-initiated movement. Rather than relying on diagnosis to determine the use of a PMD, it may be prudent to use the Hays (1) categories to determine the need.

A diagnosis such as spinal muscular atrophy impairs a body structure and consequently a function such as sitting and walking. Whereas a diagnosis like developmental delay is not associated with a body structure deficit but rather functional deficits ranging from the inability to reach developmental milestones such as fine motor dexterity to severe deficits in all motor tasks. Some children may have visual problems and some may not. Each case is different.

One may also consider the International Classification of Functioning, Disability and Health (ICF) as a framework for establishing a nomenclature for describing a mobility impairment. The level of impairment can be at the level of health condition, body structure and function, activities, participation, environmental or personal factors. Any one or all of these can lead to a child not having access to mobility and thereby participation (15).

The ICF conceptualizes a person's level of functioning as a dynamic interaction between her or his health conditions, environmental factors, and personal factors. It is a biopsychosocial model of disability, based on an integration of the social and medical models of disability. Disability is multidimensional and interactive. All components of disability are important and any one may interact with another. By way of illustration a graphic depiction may include any of all of the following levels of impairment that may warrant consideration for a power mobility device such as the Explorer Mini (15).

Without an opportunity to participate in life’s activities a child may develop additional impairments and delays. Exploration provides an infant with new perspectives and reveals new information that drive changes in a host of different psychological phenomena (3). For young children with disabilities such as CP, Spina Bifida, and other developmental disabilities, studies have shown that cognitive, social, and language development can be advanced through powered-mobility interventions (10, 13). Whereby a lack of environmental exploration leads to delays in cognition, vision, language and social skills (3). The World Health Organization has recognized that children who experience reduced mobility are at an increased risk of being denied educational opportunities, with the resulting impact on future employment and poverty (4). Therefore, it is imperative that we consider young children with mobility impairments as candidates for the Explorer Mini. 


1. Rosen, L., Plummer, T., Sabet, A., Lange, M., & Livingstone, R. (2017). RESNA Position on the Application of Power Mobility Devices for Pediatric Users-Update 201. Rehabilitation Engineering And Assistive Technology Society Of North America

2. Acredolo, L.P., Adams, A., & Goddwyn, SW., (1984) The role of self-produced movement and visual tracking in infant spatial orientation. Journal of Experimental Psychology, 38, 312-327. Doi: 10.1016/0022-0965(84)90128-0

3. Anderson, D. I., Campos, J. J., Witherington, D. C., Dahl, A., Rivera, M., He, M.,… Barbu-Roth, M. (2013). The role of locomotion in psychologicaldevelopment. Frontiers in Psychology, 4(July), 440. https://doi.org/10.3389/fpsyg.2013.00440

4. Armstrong, W., Borg, J., Krizack, M., Lindsley, A., Mines, K., Pearlman, J., . . . Sheldon, S. (2008). Guidelines on the provision of manual wheelchairs in less resourced settings. Geneva, Switzerland: World Health Organization, WHO Press.

5. Butler, P. (1988). High tech tots: Technology for mobility, manipulation, communication, and learning in early childhood.Technology, Infants Young Children, 1, 66-73

6. Butler, P.B. (1998) A preliminary report on the effectiveness of trunk targeting in achieving independent sitting balance in children with cerebral palsy. Clinical Rehabilitation, 12, 281-293.

7. Butler C, Okamoto G and McKay T. Powered mobility for very young disabled children. Dev Med Child Neurology. 1983;25(4):472–474.

8. Butler C, Okamoto G and McKay T. Motorized wheelchair driving by disabled children. Arch Phys Med Rehabilitation 1984;65(2):95–97.

9. Higgins, C. I., Campos, J. J., and Kermoian, R. (1996). Effect of self-produced locomotion on infant postural compensation to optic flow. Dev. Psychol. 32, 836–841. doi: 10.1037/0012-1649.32.5.836

10. Lynch A, Ryu J, Agrawal S, Galloway JC. (2009) Power mobility training for a 7-month-old infant with spina bifida. Pediatric Physical Therapy.;21:362–368.

11. Mancini, M. C., Coster, W. J., Trombly, C. a, & Heeren, T. C. (2000). Predicting elementary school participation in children with disabilities. Archives of Physical Medicine and Rehabilitation, 81(3), 339–347. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/10724080

12. Paulsson K Christofferson M - 1986 - Psychosocial aspects of technical aids How does independent mobility affect the psychosocial and intellectual development of children with physical disabilities.pdf.

13. Ragonesi CB, Chen X, Agrawal S, Galloway JC. Power mobility and socialization in preschool: a case study of a child with cerebral palsy. Pediatric Physical Therapy. 2010; 22:322–329.

14. Stanton, D., Wilson, P.N., and Foreman, N. (2002). Effects of early mobility on shortcut performance in a simulated maze. Behavior Brain,136, 61-66. doi:10.1016/SO166-4328 (02)00097-9

15. World Health Organization. (2001) The ICF: An overview. Retrieved from https://www.wcpt.org/sites/wcpt.org/files/files/GH-ICF_overview_FINAL_for_WHO.pdf

16. Weisz JR (1979) Perceived control and learned helplessness among mentally retarded and nonretarded children: a developmental analysis. Developmental Psychology 15(3): 311–9470 


Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS
Associate Professor in the School of Occupational Therapy at Belmont University

Dr Teresa Plummer, PhD, OTR/L, ATP, CEAS, CAPS is an Associate Professor in the School of Occupational Therapy at Belmont University in Nashville, TN. She has over 40 yrs of OT experience and 20 in the area of Assistive Technology. She is a member of the International Society of Wheelchair Providers, and the Clinicians Task Force. She is a reviewer for American Journal of OT and guest reviewer for many other journals. She has presented internationally, nationally and regionally particularly in the area of pediatric power mobility. She has authored journal articles and textbook chapters in the area of OT and pediatric mobility and access.