What You Should Know About Wheelchairs, In General / Part-I

The following is Part-I of a multi-part treatise on the various options, attachments, modifications, changes and/or variables that may be ordered, specified or added to the basic manual and/or electric wheelchair. These items appear here in random order without regard to any rank of importance, cost, availability, popularity or user-interest.

The eight wheelchair-attachments (options) reviewed here in Part-I are the following:

1. Arm-Rests 4. Lateral Supports 7. Camber

2. Controllers 5. Seat Depth 8. Cushions

3. Elevating Leg-Rests 6. "SwingAway" Joystik Mounts

4. Arm-Rests.

They may be added in many different forms and options dependent on the user’s abilities,

disability, function and preferences. They may be attached in a fixed mode (bolted), removable and

"Swing-Away" fashion, each with various options for attachment. For example, in fixed mode, they

can be bolted or welded to the frame. They can be attached with single or dual posts, flip-down

(cantilevered) on the rear-uprights or curve downward and attach to a receptacle behind the seat.

Further, they are available in various styles such as the following:

• Full Length, Fixed, Removable Armrests: These armrests have a fixed height and provide arm support from the back to the front of the seat.

• Full Length, Adjustable Height Removable Armrests: These are adjustable in height, usually with a push-pin, and provide support from the back to the front of the seat. They are often recommended if a lap tray is being used because of the stability of a long, arm-support and adjustable in height to get the tray in the optimal position.

• Desk Length, Fixed, Removable Armrest: These have a fixed height and provide arm support from the back to three-fourths of the seat.

• Desk Length, Adjustable Height Removable Armrest: Here you have the ability to adjust height and have arm support from the back of the chair to three-fourths of the seat. This allows the chair to come under a table or up to a desk.

• Space Saver Arm: The armrest curves inward to bring the armrests closer to the body.

• Tubular: These are usually flip-down with hardware on the rear uprights, or curve downward and attach to a receptacle behind the seat of the chair. There may be rolled padding on the armrest or an upholstered padded armrest can be ordered. Adjustment depends on the kind of attachment hardware.

• Swing-Away Armrests: The armrest swings to the side or back behind the wheelchair to allow for transfers or clearance.

Armrest Pads

The armrest pads attach to the armrests. They can be padded, upholstered, hard plastic or a

composite material. The non-padded upholstered pads might be a better choice if a tray is going

to be added so the tray will not rip the padding.

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2. Controllers.

They are available in two versions – integral controllers and modular controllers.

Integral controllers contain all of the necessary components in a single housing. Modular

controllers have separate components for the various functions, not necessarily in the same

housing. Both types of controllers include control joysticks. Controllers that are specific to

certain types of input include some of the following:

• Sip-n’-Puff –System is based upon the difference in air-pressure between the user’s "sipping" and "puffing" on a straw-like device for functional control of various movements of the wheelchair.

• Head-Array System uses three sensors placed inside a removable headrest for wheelchair control.

• Chin-Control System uses chin-movements in a cup-shaped, joystick control handle for wheelchair control.

• Finger-Steering System uses a finger or fingers to manipulate the joystick controller.

• Speech-Control System uses the human voice, in speech, to issue commands to the voice controller.

• Tongue-Control System uses a tongue touch-pad inserted in the upper-plate of the mouth of the user to control wheelchair movements based on experimental work done by the Dana and Christopher Reeve Foundation.

PROS

• Integral is less costly.

• Integral is simpler and easier to handle.

• Modular is more flexible and allows greater latitude in choosing the types of interfaces and controls.

• Devices such as environmental control units and communication systems can be operated through a modular system.

• Various types of "driving-controls" such as the use of a "Sip-and-Puff System", "Head-Array System", "Chin-Control System", "Finger-Steering System", "Speech-Control System" and "Tongue-Operated System" can be added with a modular system.

• With a modular system, if the user-function or the user’s ability changes (positively/negatively), the existing system can be modified or increased without replacing the entire wheelchair.

CONS

• Integral is less flexible and cannot be expanded, easily.

• Integral control is much larger.

• Integral is too large to center or offset-mount on the wheelchair.

• Modular is more expensive.

• Modular requires experience or training to set-up when adding features.

• Modular systems may require components and interfaces from multiple after-market sources to achieve the desired result.

• Components for a modular system must be compatible with existing electronics.

• Many compatibility issues may arise when setting-up a complex integrated system.

• Modular controllers increase the wheelchair’s level of complexity.

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3. Elevating Leg-Rests.

They are used to elevate the legs placing them in extended, knee-straight positions with "calf-pads"

and foot-plates which are adjustable and can be aligned for comfort and convenience. Some have an

articulating feature that allows them to be extended and become longer as the leg is elevated used

often in the case of edema or swelling in the legs.

PROS

• Maintains the leg in an extended position. This works well for those users who have limited knee flexion (knee fixed in a straight-position) or for those who require this position, after an operation.

• On a chair with a powered recline-system, powered elevating leg-rests are useful in helping a user obtain a supine-position (lying on one’s back) or a reclining position, independently.

• The ability to change the leg-positions is sometimes helpful in resolving discomfort or pain-issues in the lower extremities.

• Consider This: Are you using or prescribing these "leg-elevators" out-of-habit, out of necessity, user preference or by the vendor’s recommendation? It might be time to reconsider this item.

CONS

• With the use of these "leg-rests" comes an increase in weight of the wheelchair, itself, plus an increase in the cost.

• It has a number of moving parts that may "lock-up" or become difficult to manipulate, but rarely.

• It requires a certain amount of coordination and strength to work this item, without assis-

tance. The user must bend over to one side, depress a lever and lift the leg and device, all at

the same time.

• The extent of edema (swelling) control is questionable. In the most elevated position, the extremity is nowhere near the level of the user’s heart.

• Depending on the length of the user’s leg, elevating the leg may result in somewhat flexing of the knee.

• When the leg is elevated, it makes the chair longer resulting in the need for increased turning radius and space and possibly, re-positioning of the legs and hips.

• After a period of time, these elevating "rests" become warped or worn from the weight of supporting the legs and may become abducted (away from each other), when loaded, resulting in poor positioning of the legs and hips.

• An integral part is the leg-supporting pad that may push against the user's calves, pulling the user forward on the seat, resulting in a "sacral-sitting" (slouched) position.

• The joint at the highest-point of these devices may rub on the outside of the user's leg.

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4. Lateral Supports.

Also known as laterals, lateral-supports, lateral-thoracic-supports, trunk-stabilizers or just plain

wheelchair stabilizers. They are rectangular-shaped devices that mount to the back-posts of a

wheelchair and rest against the user's trunk. Often, they are used in pairs, one on each side of the

trunk. The main-purpose for them is to eliminate the "side-to-side" rocking of the chair and lateral

leaning. They are part of the wheelchair positioning accessories that provide a comfortable, con-

venient armrest to facilitate arm-use and rehabilitation.

Specific models can be ordered with hardware that allows these supports to "swing-away" from

the user and out-of-the-way. This makes getting in-and-out of the chair much easier. They are

available from the wheelchair manufacturer or can be purchased from a number of aftermarket

sources. These positioning accessories are most often used to increase the user's trunk-stability

and balance. These supports are sometimes used in an effort to control "spinal-scoliosis" ("S-

shaped" curvature of the spine).

If the user’s trunk can be placed in an upright, neutral, sitting-position but the user cannot

maintain this position, the supports can be placed opposite one another, on each side of the

trunk. This technique adds the needed external support to hold the user in position. Many users

and professionals think that these supports must be placed exactly opposite each other on the trunk.

This is not true and, in certain cases, may result in poor performance results and extreme

discomfort to the user.

In order to work well, these devices must be in contact with the user’s trunk. If they do not make

contact, support is not possible. If they are too tight, the user may have a problem with breath-

ing. If they are placed too low, the support is lost and the trunk may "lean" over the supports. If

placed too high, they may impinge on the armpit and cause damage to the nerve fibers from the

spine to the neck and arm, irritate the surrounding skin while restricting shoulder and arm move-

ments.

PROS

• Aids in trunk support and stability.

• Improves balance and posture.

• Helps maintain the user in a functional position. .

• Prevents further postural decay.

• Diminishes the need for repetitive repositioning of the user during the day.

• Improves appearance. .

CONS

• If placed too low, they are ineffective.

• If placed too high, they may irritate the armpit, spinal nerves, surrounding tissue limiting shoulder and arm movement.

• May be difficult to mount to the "back-rest" in the proper location.

• When the pad is under pressure, the "swing-away" feature may become difficult to operate.

• Contact of the entire pad against the body is difficult to position since there are no adjustments for angling the pad in or out.

If the user changes position, the supports will now, most likely, not be aligned, correctly, any more. In

addition, they add another layer of complexity to the entire chair.

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5. Seat Depth.

Wheelchair seat-depth is measured from the front to the back of the seat. To determine the

exact size, you need to measure the distance from the front edge of the seat to the back where the

seat meets the back-upright. The measurement is taken from the back of the pelvis (furthest back

part of the buttocks), forward to the back of the knee. Make sure that each leg is measured

separately.

If you have decided on an add-on back, you will need to allow for this. If the chosen back takes

up seat space in front of the back uprights, you will have to add that amount back into the

formula. If not, you will be scratching your head wondering why the seat appears so short on the

finished product.

With no add-on back: (measured length) - (2" clearance) = depth

For chairs with an add-on back: (measured length) – (2" clearance) + (overlap-of-back on seat)

= depth

Source listing of add-on wheelchair back-suppliers =

www.usatechguide.org/techguide.php?vmode=1&catid=205

If there is a leg-length discrepancy (differences in leg-length), custom upholstery, seat pans or

inserts can be ordered from the wheelchair manufacturer or from aftermarket suppliers. Many

cushion manufacturers will also custom make their products to accommodate these differences.

PROS

• A proper wheelchair seat-depth will afford the user increased pressure reduction.

• It will also enhance comfort and will promote improved sitting posture.

• A shallow a seat as possible will assure a shorter wheelchair frame (manual wheelchair)

resulting in a lighter chair with a decreased turning radius and easier transporting and storage.

• A longer depth will serve to distribute pressure over a greater area (the surface area of the seat) thus reducing pressure in any given place. (This does not hold true if the user is sitting in the knees-up position with only the "sitting-bones" making seat contact. The pressure will still remain on these bones no matter how deep the seat is. If the thighs do not make contact with the seat, they will not aid in an even pressure distribution.)

CONS

• An excessively long seat will push against the back of the leg or in the area of the fold on the back of the knee causing the user to be pushed forward on the seat and into a slouched position. If left unresolved in patients with no sensation or feeling in the lower extremities, this situation may also result in sores and/or wounds to the back of the leg.

• An overly-deep seat will not allow the user to sit all the way back against the wheelchair-back.

• If the user is forced forward on the seat, most of the weight will be located forward on the

wheelchair making the chair harder to push.

• Long seats will also add weight to the chair.

• Excessively short wheelchair seat-depths will result in increased pressure to the seating area

resulting in less surface area. This may increase the risk of tissue trauma.

• The amount of support offered by the seat will also diminish possibly causing poor posture.

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6. "Swing-Away" Joystick Mounts.

A mounting arm for the joystick with an articulating (hinged) joint that makes it possible to swing

the control away and back. Most models have a tension mechanism for locking the arm into the

forward position. These items can be obtained from the wheelchair manufacturer or a number of

aftermarket sources. Depending on the source, there are slight differences in design. These

devices are primarily used to allow power wheelchair users to get closer to and under tables,

desks, workstations, etc.

Because of the great flexibility in aftermarket products, "joy-sticks" can be mounted just about

anywhere desired on a wheelchair. There are two types of mounts – bolted-on (permanent and

usually slimmer) and quick-release (requiring a release-device or lever including suction-cups).

The most complex part in configuring a custom, joystick controller can be in determining and

implementing the mounting. The layout of the buttons, comfortable placement of the hands and

obstructions determine the dimensions of the control panel and the placement of the controller

box. Because the mounting depth is determined by the length of the joystick's shaft, different

models of joysticks have different distances between the top of the mounting-plate and the

bottom of the ball-top meaning some joysticks should be installed much closer to the surface.

The main goals are to place the joystick at a height suited to the "play-style" of the user and to

have the joystick-body hidden securely under a smooth surface. Many users like to rest the side

of their palm on the panel while using the joystick at a specific, relative height. If you feel like

you need a more detailed analysis of the "mounting-depth", you should get a feel of the actual

joystick, itself, to determine how deep it should be placed.

In the United States, there are at least five after-market manufacturers of joystick-mounts ranging

in price from $ 20.00 to $ 300.00, custom-mounted.

PROS

• Makes it possible to move the joystick "out-of-the-way" to get closer to tables, desks, and workstations and under counters.

• Increases functionality, comfort and independence.

CONS

• The position locking mechanism or the moving parts may loosen after some time, making the joystick-box "wobbly" and difficult to lock and/or hold in place, on rare occasions.

• User may not be able to manage the device, independently.

• This device is, often, an optional upgrade to the wheelchair and will add extra expense.

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7. Camber.

Camber is the angle made by the wheels of the chair. It is the angle between the vertical axis of the rear-wheels and the vertical axis of the chair when viewed from the front or rear. It is used in the design of steering and suspension. If the bottom of the wheel is farther out than the top (away from the axle), it is called negative camber. Tilted-rear-wheels, a popular feature on racing wheelchairs is being seen more and more on wheelchairs that are used for activities of daily living.

One of the advantages of camber is that it provides better lateral static stability for the wheelchair as a result of the greater distance between the low, bottom-points of the two wheels. This is especially advantageous when frequent sideways movements are needed as in wheelchair basketball. It can be described as an angling that brings the top of the wheels closer to each other.

In a study conducted in Holland, eight, non-impaired subjects participated in a wheelchair exercise/test using a motor-driven treadmill in order to study the effect of rear-wheel camber on wheelchair movement for six shoulder muscles which was an integral part of the study. The test consisted of four runs with rear wheels in 0°, 3°, 6° and 9°-degrees camber at speeds of 2, 3, 4

and 5 km/hr. There were no significant effects on oxygen-usage, heart-rate or mechanical efficiency.

Camber angle alters the handling qualities of the suspension design; negative camber improves the grip when cornering. This is because it places the tire at a more optimal angle to the road, transmitting the forces through the vertical plane of the tire, rather than through a force across it. Another reason for negative camber is that a tire tends to roll on itself while cornering. If the tire had zero camber, the inside edge of the contact point would begin to lift off the ground, thereby reducing the area of contact. By applying negative camber, this effect is reduced, maximizing the contact point. Note that this is only true for the outside tire during the turn; the inside tire would benefit most from positive camber.

On the other hand, for maximum straight-line acceleration, the greatest traction is attained when the camber angle is zero and the tread is flat on the road. Proper management of camber angle is a major factor in suspension design and must incorporate not only idealized geometric models but also, real-life behavior of the components such as flexing, distortion, elasticity, etc. What was once an art has now become more exact and scientific with the use of the computer that can optimize all of the variables, mathematically, instead of relying on the experiences and intuitive estimations of engineers. As a result, the improved handling of wheelchairs has been dramatic in recent years.

However, excessive camber angle can lead to increased tire wear and impaired handling. As camber is increased, the width of the wheelchair across the bottom increases. This adds lateral-stability to the system by increasing the wheelchair footprint. If too much camber is added, there may be a problem getting through the doorways. The amount of camber required for ordinary, daily use is not the same as that that is required for wheelchair sports. The amount of camber introduced is measured in degrees where the higher the number, the more camber or angling. Some more expensive models of wheelchairs have methods of adjusting the camber.

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Besides the greater stability of cambered wheelchairs, cambered rear-wheels provide an easier

reach to the hand-rims and less hampered arm movements during push-and-recovery movement leading to a less strenuous propulsion technique. Thus, camber would be more efficient with less

arm spreading and stabilization. A study on chair characteristics during the 1980 Paralympics showed a trend of increased success of the athlete with increasing camber. The most successful athletes had wheelchairs with a camber.

Off-road vehicles such as agricultural tractors generally use positive camber. In such vehicles, the positive camber-angle helps to achieve a lower steering effort. Also, some single-engine aircraft that are primarily meant to operate from unimproved surfaces such as bush-planes and crop-dusters have their main wheels equipped with positive-cambered wheels to better handle the deflection of the landing gear as the aircraft settles on rough, unpaved airstrips.

Caster is the tilting of the steering-axis either forward or backward when viewed from the side of the chair. A backward tilt is positive and a forward tilt is negative. Caster influences directional control of the steering (in an automobile) but does not affect the tire- wear and is not adjustable. On an automobile, caster is affected by the vehicle height. Overloading the vehicle or a weak or sagging rear spring will affect caster. Since we are talking about a wheelchair, caster does not come into play.

PROS

• A wider footprint ads lateral stability to the wheelchair.

• Camber re-directs forces to soften the ride.

• Camber places the push-rims in a more ergonomic position for pushing. It is more natural to push down and outward.

• It protects the hands when pushing in tight area since the bottom of the wheels will make contact first with walls and doorframes.

• There is less strain on the shoulders since the plane of the wheel is closer to that of the shoulder.

• Makes turning quicker.

• Gives the wheelchair a sportier look.

CONS

• The wheelchair will be wider.

• Cambering will add a cost to the chair.

• An excessive camber may cause the wheels to rub against the armrests(s), side-panels or

against the user.

• Diminished traction and uneven tire wear on a conventional tire.

NOTE: Conventional tread placement is centered on a tire. A cambered-tire rides on the

inside edges of the tire. Some manufacturers make tires with offset treads to

compensate for cambering.

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A(II)

8. Cushions.

An unfortunate fact-of-life for many wheelchair users is the potential for acquiring pressure

sores. These can rob a victim of their health, independence and quality of life. The reasons

have been identified and documented through research and experience. Uncontrolled pressures,

inappropriate technology, poor nutrition, incontinence, lifestyle issues, stress, poor hygiene, poor

care and aging are the usual causes for these pressure sores with the wheelchair cushion being the

usually-blamed culprit.

There are other possible contributing factors that need to be examined. Pressure sores on or near

the seating-area does not, necessarily, begin or end with the cushion but it may be the easiest

place to start the investigation. A good, upright sitter, with a "sacral sore", who does not go into a

"sacral-sitting" position, probably, did not get the sore from the cushion. The cushion was,

probably, nowhere near this area while the individual was seated in the chair. (Sacral-area-sores

are pressure sores (from slouching and/or poor posture) that are near the anal canal, deep and

contaminated by bladder and/or rectal-contents that can be cured by techniques such as good

wound care, physician techniques and proper-fitting cushions.)

Other reasons include bed-surface, recliner-chair, a gurney, turning-frequency, stretcher, the

shower or commode equipment with seat-cutouts, lift-slings and lumbar-pads. Questions should

be asked such as "How often does the patient use these devices; for what period of time; is the

equipment being used properly; is it in good working order?"

When it comes to pelvic-area sores, the cushion will, most likely, be the cause. The pelvic-area is

in contact, regularly, with more than just the wheelchair-cushion, itself. Search-for-causes should

begin with car seats, airplane seats, unpadded shower benches and chairs, transfer-boards and

anything else that the victim sits in-or-on, besides the wheelchair. Sitting-up in bed with the hips

flexed more than 30º will affect the pelvic area, considerably. Dragging this area across a trans-

fer-board or hard-landing surfaces, sitting on a transfer-sling all day, not doing weight-lifts or

shifts and over-extended "sitting-times" should be avoided at all costs.

Investigations should be thorough. Check the cushion - make sure it is in good condition, adjust-

ed and placed properly. Pummels (rounded-knobs) are effective but not when the cushion is

placed on the chair, backwards. Air-cells are great pressure reducers but not when they are facing

downward. Over-or-under inflation of air-flotation-cushions can cause many problems. Worn out

cushion-bases and seat-hammocks can inhibit pressure-reducing characteristics. Confirm that the

user is actually able to place themselves in proper alignment with reliefs and seat-contours.

Some cushions have been known to have their covers on backwards. Look at the cover and con-

firm that the cushion is aligned with the cover. Often, strange items are found under the cushion

or cover such as wallets, keys, books, assorted supplies, medicines, etc. When this occurs, they

change the cushion-dynamics and become a point of increased pressure. It should be clear by

now that wound prevention and pressure management involves more than just "swapping"

cushions. The contributing factors are varied, complex and changing. In most cases, it is imposs-

ible to single out just one cause of the problem and pronounce it as the primary offender. It is a

multi-dimensional problem. The solution is also multi-dimensional and should be approached

that way. Cushion-problems do not make the other possible related problems non-existent.

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A stable pelvic position is the most important key to prevent "sacral-sitting" meaning with "the

proper posterior pelvic tilt"; i.e., no slouching, no slumping and no forward-sliding without any

postural limitations and/or deformities. The two main reasons for "sacral-sitting" is that the seat-

depth is too long and/ or an incorrect seat-to-floor height. The correct seating-position is when

the hips are all the way back in the chair against the back-rest and one-to-two inches from the end

of the cushion to the back of the knee. With a stable pelvic-position, focus can be on upper-

extremity positions and what back-rest to chose.

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