A Powered Mobility Device for Children with Tetraphocomelia


An innovative powered mobility device, unlike any conventional wheelchair, was developed for the very young child (1-3 yrs.) with tetraphocomelia. Mobility is a critical component for a child's cognitive and social development, especially during the first 3 years of life. Movement provides a sense of independence and competence derived from exploring one's environment. However, when this experience is restricted during these formative years, as in children with tetraphocomelia, there is a diffuse and lasting impact (Becker 1975).

Present mobility management has not reflected a commitment to providing this locomotive opportunity for the very young child. Motorized wheelchairs have traditionally been utilized when a child is approximately 5 or 6 yrs. of age and older. Prior to this age, emphasis has been placed on merely promoting developmental motor skills or use of braces, standing devices and swivel walkers. Although the motorized wheelchair may be the vehicle of choice for the age range greater than 5, it may not be a viable option for a young 12 month old child, since it may be developmentally inappropriate or socially unacceptable for the parents. Commercial availability of an appropriate motorized vehicle for a young disabled child is extremely limited. This lack of availability prompted us to develop the mobility prototype through a collaborative effort between Alfred 1. duPont Institute Physical Therapy Department and engineering students at the University of Delaware. Even though this device was designed with a specific 2 year old tetraphocomelia child in mind, the functional specifications incorporated flexibility so the device would be a versatile tool for children with various disabilities.

The most salient functional specifications as determined by the physical therapist include: 1) a powered device providing independent mobility to a young 1-3 yr. old child, 2) proportional control drive joystick with adjustable positioning so as to be used with the head, chin, upper or lower extremity or limb buds, 3) adjustable seating in an upright frame into which inserts could be attached if desired to accommodate growth (also accommodation of bucket prosthesis), 4) compactness, durability, portability, servicability, reliability, and safety, and 5) low profile with mounting potential for some children, and at a level to facilitate interaction with peers.

This motorized prototype is designed to enable disabled children from 1-3 yrs. to have independent mobility with their peers. The modular design is composed of a frame, seat, and body. A round 28" diameter molded Kevlar(r)/styrofoam shell supports the child on all sides. A rubber bumper is added to absorb impact of collisions as well as to protect the home environment. A metal seat frame is attached to the shell. To this, a 2 piece removable back and seat can be attached or another custom insert could be used if so desired. A cutout area in the seat frame accommodates a bucket prosthesis if needed. The controller chosen is an ABEC proportional drive joystick mounted on a gooseneck so it can have multiple position capability. Its conventional drive coupled with the round shape promotes maneuverability. Two motors and two rechargeable 6 volt gel batteries are utilized. Speed can be preset and is adjustable to up to 2 ft./sec. An on/off safety button is provided for adult supervision.

Two children with tetraphocomelia initially tested this device. The first child, a 2 yr. old girl, needed to use the bucket accommodation, the ABEC control at her chin and supportive straps. Within a few minutes, she was quite adept at maneuvering the device. The second child, a 14 month old boy, was able to climb into the seat and mobilize the cart via his upper limb bud. He too was safely carousing the area within a few minutes. This particular child loved this new "toy" and was not too amenable to ending his fun. Given the device's unique ability to rotate about its axis and given its round shape with bumper pads, the cart is easily maneuverable out of a corner unlike conventional wheelchairs. Also, its round shape and bright yellow color appealed to the child's sense of interest. Its likeness is that of "an amusement park's toy bumper car." The device is presently undergoing further trials by therapists on a variety of children.

This innovative device meets the needs of younger children (I - 3 yrs.) who require independence and mobility without the constraints of more conventional wheelchair prescriptions. This device, although designed with the phocomelic population in mind, is quite versatile and is applicable to populations such as spinal cord injury, arthrogryposis and spina bifida.

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