Designers: Sam Lipman, Nicole Rothfusz, and Kelly Waldman
Client Coordinator: Charlotte Hughes, PT, Orange County Schools
Supervising Professors: Kevin Caves and Richard Goldberg
INTRODUCTION
Molly is a middle school student who uses a manual wheelchair due to a spinal cord injury. She has paraplegia at the T-3 level and does not have motor control or sensation below mid-sternum, but has full movement of her head, neck, shoulders, arms, wrists, and fingers.She is strong in both pulling and pushing motions. Molly is able to maneuver her manual wheelchair independently and can transfer independently between horizontal surfaces that differ less than 2 inches in height using a depression lift in which she lifts her body weight up with her arms.
Molly is in a technology class where the other students sit on stools at elevated tables. She is currently unable to do this because the stools in the classroom do not provide adequate support and she is unable to raise and lower herself the ten inches between her wheelchair and the height of the stool. In order to work at these elevated tables, we developed a device that will enableher to raise and lower herself independently, while also providing the necessary cushioning and postural support..
STATEMENT OF IMPACT
The physical therapist reported “Molly is excited about the device as it allows her to use the same desks as her peers and it will give [Molly] access to the lab table for years to come.” Additionally, while utilizing the device, Molly exclaimed several times: “I feel so high!” and “I’m higher than a table for once!”
TECHNICAL DESCRIPTION
We modified a commercial drafting chair, the Global Deluxe Fabric Drafting Chair (purchased from Staples), which uses a gas spring to adjust the height of the chair over a ten-inch range. Like typical office chairs, when the user unlocksthe pneumatic gas spring assembly, the chair rises when no weight is placed on the seat, and lowers when the user is seated. New adjustable armrests and support poles were designed so that the client can perform a depression lift, de-weight the seat and subsequently activate the pneumatic gas spring assembly to raise the chair in a series of increments. Once the client raises the chair to the desired height, the chair mechanism can slide forward along tracks, so the client can pull herself in to work at the elevated table. The device is pictured in Figure 1.
We made several modifications so that Molly could deweight herself to easily raise and lower the chair. We added a bicycle brake handle and cable to pull on the lever mechanism that unlocks the gas spring. The brake handleis attached to the right armrest and when squeezed, the brake lever pulls on the cable, which lifts the unlocking lever. The chair will go up if the client puts no weight on the seat by performing a depression lift, and down when she sits in the seat.
To facilitate the depression lift, we constructed armrests that can adjust in height. A pair of vertical, 4’ long 1” square aluminum tubes supports the armrests. Each tube has four 3/8” bolts driven through them to create different supporting heights for the armrests. The armrests are constructed from 2”x4” wood, which are each attached to 2”x3” rectangular tubes of ¼” thick pieces of aluminum that are 7” in length. There is a 1 1/8” x 2” rectangular hole cut from the back of the metal tube. The vertical supporting bars fit through this hole, so that the armrests can slide up and down the supporting bars, and stay in place at the height of any of the bolts.
The modified drafting chair is mounted to a custom T-shaped wooden base constructed from two pieces of plywood that measured 25”x28’x1/2”. The plywood bases are connected via four side drawer slides, to allow the client to slide the chair up to the desk to work as close as she would like. Each pair of drawer slides can support up to 100lbs. The top base piece has six non-castor wheels that support the device when the sliders are in the open position as the client transfers in. The two wheels in the back also allow the device to be easily transported between classrooms.
For increased safety, it was necessary to prevent the base from swiveling while transferring. A locking mechanism was fashioned out of a 1 ½”x3” rectangular aluminum tube with a 1/8” thickness. The mechanism catches a horizontal stabilizer support for the armrest poles and locks automatically when the seat is lowered to its lowest position. This prevents any swivel movement while the chair is in the lowest position and enables a safe transfer.
The total cost of the device was $486.