Sheila Buck B.Sc.(OT)Reg.(Ont.),ATP

GOALS FOR POWER MOBILITY

Enhancement of social skills – taking control over the environment, decision making for encounters, self esteem, body image, responsibility, risk taking, interpersonal relationship development
Enhancement of cognitive skills – cause and effect, judgment, decision making, expressive language development
Joint protection and pain management
Energy conservation
Compensation for limb dysfunction
Reduction of associated reactions from increased stimulation during manual wheelchair propulsion
Early enhancement of visual/perceptual skills such as object permanence, spatial relations, distance and directions

SCOOTERS

Clinical Considerations:

Arthritis
Heart conditions
Breathing difficulties
Leg vascular difficulties/diabetes
Obesity
Lower leg amputation
Degenerative disc disease
Early stage Parkinson’s disease

Considerations for prescription:

Maintained unsupported forward reach for heart/breathing difficulties – angled or height adjustable arms
Suspension for spinal concerns
Mobility around the tiller for contracted knees/feet from arthritic changes
Angle of platform for foot swelling/pain from arthritic changes – need for position changes while driving
Elevating seat for arthritic hips – higher transfer heights and ongoing height changes for hip/knee angle discomfort
Seat, tiller lever, key and charger access for limited forward back flexion or limitations in reach and grip/manipulation
Seat height, width, depth for seating to promote posture and prevent further postural control problems
Thumb/finger control and pain levels for maintained grip
Basket position and ease of movement/access – as limited by arm/back function, heart and breathing conditions
Stability with limitations in visual field or perception – 3 or 4 wheel
Base length and ¾ wheel for maneuverability as well as foot/leg room

POWER WHEELCHAIRS

Clinical Considerations:

Progressive disorders with neurological changes

Adjustable electronics (programmability) for speed, torque, sensitivity, digital compatibility for switch options
Future option for fixed or power tilt
Seat width adjustability
Drive wheel position based on previous learning, stability of trunk, suspension
Power base style chair

Cognitive limitations

Programmable for low speed/high torque
Stable base
single foot plate or tapered footrests to reduce forward scraping
drive wheel position based on ability to judge distances for turning radius – rear or mid wheel may provide the best option

Postural limitations due to tone, balance, orthopedic changes

need to determine if limitations are progressive or stable
programmable electronics, may require short throw
ability for center of gravity shift to maximize weight over drive wheel
space under front of seat for flip down pommels

Transfers

room for maneuverability in front of chair for pivot transfers – watch for shroud, flip up footplate platform, mid wheel front stabilizer wheels
seat height based on frame height
ability to access toilet, bed

Growth and weight changes

adjustable seat frame for width/depth, height to floor
frame/motor strength for weight/warranty
suspension for high or low weight clients
seat frame adjustment for center of gravity as weight changes

DRIVE WHEEL POSITION

Rear Wheel Drive: system center of gravity is well ahead of the drive wheel position

Mid Wheel Drive: system center of gravity is somewhere over the drive wheels

Front Wheel Drive: system center of gravity is well behind the drive wheel

Considerations for Drive Wheel Placement

Turning Radius/maneuverability:

initiation of turn: based on drive wheel placement – turn must be started at the point where drive wheels are far enough into the space into which the turn is being made
consider clearance for lateral parts of the chair (arm pads, joystick, tire) and length (fore or aft) of the chair.
Consider width of doorway and hallway and clearance on the entered room side
Consider the swing of the chair: rear wheel – front end swing

mid wheel - front/rear swing

front wheel – rear end swing

Suspension/stability:

Shock absorption or maintaining wheel contact on uneven surfaces
All centre/mid wheel drive chairs require suspension to maintain wheel contact – need to consider the degree of travel of the suspension to avoid hang-ups on surface irregularities or slope transitions

Centre of Gravity/Traction:

Shift of seat on frame of chair – important to offset larger seating systems of client weight to maintain center of gravity of client over the drive wheel or center mass of the chair
mid wheel – if c. of g. is too far forward, chair will pitch forward during braking or deceleration
rear wheel – if c of g is too far forward over the casters – increased steering resistance and reduced traction
front wheel – if c of g is too far rearward – less front wheel traction especially on inclines

Obstacle Climbing:

based on location of drive wheels, electronic reading of motor speed, play of suspension or stabilizer wheels, size of front caster

Electronics : Adjustable for a variety of uses – standard factory settings rarely are adequate for each individual use. Turning down high speed, does not adjust each parameter accordingly. Need to determine need for control vs. speed vs. torque vs. acceleration, turning. Deceleration based on client use and functional status.

CLINICAL CONSIDERATIONS FOR POWER PRESCRIPTIONS

Light weight “portable chairs”:

good hand function with less orthopedic changes
require more seating or support than found on a scooter, or need maneuverability
mainly indoor or in/outdoor on flat surfaces or urban concrete
can adapt to lower seat to floor heights for independent transfers
lower cost – more portable – more often folding but can also be power base style
less adaptable for swingaway controls – hinder access
not recommended for progressive disorders that need electronic or seating changes
not for those of higher personal weight or requiring suspension
available in power base or folding cross brace frame

Conventional Folding Frame:

some modification and customization within electronics
increased motor power for alternate terrain
lower cost than high end power base
swingaway controls
may or may not accommodate tilt

Power Base:

higher end electronics for full customization
higher cost
durable with optional suspension
ability to add power tilt, seat lift or fixed tilt
best suited for clients with poor postural control, pressure problems or predictable changes in seating and/or electronic requirements

PRESCRIPTION JUSTIFICATION

knowledge and full exposure of diagnosis, presenting medical condition, postural and mobility status and pressure/weight shift abilities
awareness of problems and potentials for functioning through mobility, postural control and pressure relief
postural evaluation including a mat assessment, and assessment of skin integrity, strength, coordination, tone, associated reactions, balance and sensation
assessment of neuropsycholigical functioning including cognitive/perceptual/visual, insight, ability for new learning and relearning
social support system and ongoing financial status
ability to set objectives/parameters for mobility
equipment prescription and use as affected by seating support/control and positioning of hand/arm for control, final set up of electronics and center of gravity
sizing and it’s affect on accessibility and use in the home as well as the community