Manual Wheelchairs Flashcards
What dictates the design and selection of a wheelchair?
Individual’s specific needs
First Self-Propelled Wheelchair
1655 - Stephen Farfler (paraplegic watchmaker) built a 3-wheel hand crank chair
E&J Chair
First collapsible light weight wheelchair designed by Harry Jennings (1933)
Three main types of manual wheelchairs
- Tilting wheelchairs: allow frequent changes in position, for people who are not able to sit upright without mechanical aid
- Heavy-duty wheelchair: > 400lbs
- Children’s wheelchair: number of positions (sitting, standing, laying down)
-Bonus: All-mountain, tank
Four factors considered in wheelchair assessment
- Type of disability: quad vs para vs amputee vs immobility
- Level of activity: active vs sedentary
- Degree of control: manual vs motorized
- Physical parameters: height of chair back, degree of stability, use of hand, comfort level
Characteristics of manual wheelchairs
-Propelled by the user, requires upper body strength (injury below C6)
-Easy to push
-Unlimited range
-Simple to maneuver, easy to transport
-Exercise, but can lead to repetitive injuries
Weight of wheelchairs
- Lightweight (<34 lbs): not adjustable
- Ultralight (<30 lbs): titanium and aluminum can weigh under 20 lbs. More expensive than lightweight, highly adjustable.
Types of frames
- Rigid-Frame: consists of a rigid frame, back folds down and wheels have quick release; very lightweight
- Folding-Frame: has an X-frame with two locking mechanisms; not as durable due to moving parts
Components of a standard wheelchair (8)
Armrest, push-handle, pushrim, tires, wheels, casters, footrest, brakes
Wheelchair Fitting (7)
- Seat Width: hips + 1”
- Overall Width: narrower is more responsive but more tippy
- Seat Depth: pelvis to back of shin - 1”
- Overall Depth: seat length but additional length due to footrest
- Seat Height: function over comfort
- Footrest Length: long enough to accommodate user’s legs
- Back Height: varies a lot
How do you choose your ideal wheelchair?
Experience - adjustable wheelchair until you decide what you want (angle and height of backrest, center of gravity)
What is the main issue with manual wheelchairs?
Long term usage lead to high risk of upper extremity injury. Most common ____:
- Musculoskeletal - shoulder (most mobile joint, but least stable; can’t replace the hip)
- Neurologic - wrist (carpal tunnel syndrome - pressure on the median nerve)
Propulsive force
Propulsion comprises of a pushing and recovery phase.
Pushing: hands make contact and apply force to rims
What is the fraction effective force equation?
FEF= Fm*|Ftot|^−1x100 (%)
(Fm - tangential component)
What is Mechanical Efficiency (ME):
The ratio of work accomplished to the energy expended to do this work
ME = F/d
4 types of Propulsive Cycles
-Semicircular (16%)
-Single loop over propulsion (45%)
-Double loop over propulsion (25%)
-Arcing (14%)
What muscles are used in the push phase? (8)
Biceps Brachii
Anterior Deltoid
Triceps Brachii
Flexor Carpi Ulnaris
Extensor Carpi Radialis
Pectoralis
Trunk Flexors
Rotator Cuff Muscles
What muscles are used in the recovery phase? (2)
Posterior Deltoid
Triceps Brachii
What muscles in the rotator cuff are used? (4)
Works to stabilize the shoulder.
Supraspinatus, Infraspinatus, Teres Minor, Subscapularis
Slides 29-44
Understand them
What factors affect the vehicle?
Resistive force - air resistance, bearing resistance, rolling resistance.
Higher rolling resistance results in less propulsive momentum generated.
What is the equation for rolling resistance?
Froll = μ1(N1·R1^-1) + μ2(N2·R2^-1)
μ - friction coefficient, N - relative weights, R - radii
What factors influence RR (most - least)? (8)
Toe (100%), tire type (90%), surfaces (80%), tire pressure (32%), load (20%), load distribution (25%), casters (not really), camber (none)
What is the best wheel position wrt shoulder?
Closer the rear wheel axel is to the shoulder improves the efficiency of the push?
