Life on Wheels (59 page)

Footrest clearance is also an issue when making a transition from a sloped surface—like a ramp—to a level one. If you are moving forward down a somewhat steep surface (the world does not necessarily conform to the recommended 1:12 standard), then your footrests could potentially make contact with the level surface while the rear wheels are still coming down the slope. This contact at the footplate will stop you cold. This would cause the chair to tip forward, dumping you out, lying on your face or your side! In other words, don’t tempt the issue of footrest ground clearance. It is extremely important.

Whether you want your seat to be higher than the minimum needed for footrest clearance depends on a number of factors. The higher you sit, the better you can reach your cabinets in the kitchen, shelves in stores, or a bookshelf at work. Your visibility will also be a little better. Be sure, though, that your knees will be able to fit under tables and desks. On the other hand, it might be important for you to be closer to the floor, perhaps for your work.

You might be a user who doesn’t use footrests—common for people who have had a stroke and have the use of at least one leg. Your seat height, then, will be determined by being able to get your feet in solid contact with the floor so you can use them to help propel the chair while you are able to sit fully back in the chair. This is also therapeutic, allowing you to continue to make use of all the physical capacity available to you.

For people who have less agility and strength, being at the same level as the surfaces you transfer to—such as your car seat, your favorite chair, or your bed—would be a higher priority. When the chair seat is at a different height, you or someone assisting you, must exert some extra strength to deal with that change in height. Your body will need to be lifted somewhat onto a higher surface or kept from essentially being dropped onto a lower surface.

If you sit too low, you might strain your neck in conversation with people who are standing next to you. Some people feel that, when they sit low, they are less charismatic or appear inferior to those around them. They feel “looked down upon.” However, seat-height preference is an individual matter. Some folks are just happier at a higher or lower level. Make sure you take time to consider all the practical, psychological, and personal aspects brought to bear by the height of your chair. Remember that the height of your seat has an effect on the optimal relationship of your arms to the wheels of a manual chair, and that you must account for the thickness of your cushion during this part of the process.

Your chair seat does not necessarily need to be parallel to the ground. Seats can slope down toward the back. The angle of the seat compared to the ground is sometimes called “seat dump” or “squeeze.” (For an example of extreme seat dump see Figure 4-2.)

Having some degree of seat dump means that more of your weight presses against the chair back, making you feel more stable in your seat. People with higher-level spinal disabilities—and therefore less control of muscles in their torso, which would provide greater stability—gain security and safety by using some seat dump. Manual chair riders use whatever amount of seat dump they need to exert the most push with less effort through their arms and shoulders while remaining stable and symmetrical in their seat.

Many chairs allow you to adjust seat dump. Raising the rear axles to a higher position has the effect of lowering the rear of the chair and, so, increases the seat dump. It might also be possible to raise the caster height, achieving the same effect. Many rigid frame chairs are customized with fixed front and rear seat heights, so changing the casters would be the only way to adjust dump once the chair is delivered.

There are tradeoffs for the advantages of seat dump, however, including health risks such as an increased possibility of spinal curvature and back strain. The more your knees come up relative to your thighs, the more your pelvis rotates backward. Your spine, attached to your pelvis at the bottom, then gets rotated to the rear, flattening out your lumbar curve, which helps the spine do its remarkable work of flexibly supporting your torso and head and shoulders. Too much dump can also make transfers more difficult, your body wanting to slide back down the angle of the seat with gravity. Consult carefully with your therapist and dealer about the best seat angle for your needs.

Until recently, cloth or vinyl sling backs that necessarily had to fold with the chair were the only choice. Flat backs provided no lumbar support, lateral trunk stability, or accommodation of people with more advanced orthopedic or neurologic needs.

Aware of the need for better postural support, chair and cushion designers directed their efforts to making other options available. Designers gained more freedom with the advent of rigid frame manual chairs and modular power chairs. Rigid frame chair backs pivot down against the seat, rather than closing sideways, so the back upholstery does not need to collapse. Power chairs used to be folding chairs with motors and controls tacked onto them. Now the back can be designed as an independent element with more shape, support, and upholstered comfort.

The folding chair, however, as we’ve seen, has not completely disappeared and has its place for some users. A now-common design enhances the traditional cloth back by adding a series of horizontal straps down the inside of the chair back (Figure 4-10). The straps are tension adjustable so that each strap can be individually tightened or loosened according to the need for support at a particular point in your back. A tension-adjustable back can still provide support only as far forward as the vertical supports of the back, but it is a vast improvement over a back that is simply a piece of material.

Another approach to back support is a rigid back with deep upholstery. These products typically allow you to adjust lumbar support. To install this kind of chair back, the standard cloth back is removed entirely, support clips are added to the vertical canes of the chair, and the new back is hung on these clips. For a folding chair, this back must be lifted off before the chair can be folded.

If you will be pushing a manual chair, you’ll want to compare the benefits of improved back support against the additional weight of a more supportive back. Keep in mind that, with extra back support, you will be able to maintain more firm contact with the back of the chair as you push, enabling you to exert more force on the wheels. You will also want to take into account whether the back can remain on the chair when you collapse the back down. If you drive a car (as compared to a ramped van), you probably break the frame down to its smallest components, so a back that can remain in place would be desirable. Other back designs involve special clips that the back slips onto and off of.

If your strength and balance are more limited, your need for other back support features increases. For instance, if you have limited side-to-side stability, you can choose a back cushion that wraps around you, curving to your sides to help support you laterally. If your balance is precarious or you tend to slip easily from neutral posture, you might require additional lateral-support accessories, a hip or chest seat belt, or both.

For people whose bodies are not symmetrical, the chair back might need to be customized by a rehabilitation engineer who works closely with your therapist and wheelchair supplier. This more-advanced approach can involve making molds of your body to make a highly specialized support system specifically for your needs. Some positioning centers have newer technology that can actually take a computer model of your body shape by having you sit in a special device loaded with sensors that can map your body’s shape. The data are then used to manufacture a support system for you.

You need sufficient support for your upper back, not just the lumbar curve. If you are unable to use your legs, your balance is limited and your center of gravity is higher up your trunk. Simple physics is at play here—if your center of gravity is higher up, you are going to fall over more easily. If you are paralyzed as high as your abdomen and trunk, without control of those muscles to stabilize your upper body, you will need a higher back to provide you support and stability. Too low a back might leave you unnecessarily fatigued from having to balance yourself rather than allowing the chair back to carry you.

If you use a power chair because of a lack of strength or stamina but have normal control of your torso muscles—such as would be the case for users with multiple sclerosis—then you would need less height. You would be able to preserve the free range of motion of your upper torso and shoulders. Some people who have higher spinal cord conditions and are using a power chair will need their back fully supported, maybe even a headrest. Since your ability to move your upper torso is limited, being more fully carried is going to be the higher priority. Use of a tilt-and-recline system certainly requires a full-height back with a headrest.

At the same time, lower chair backs have become popular on manual wheelchairs, partly as an image issue because they lessen the presence of the wheelchair. Your chair back should be high enough to provide the support mentioned above, but not so high that it limits your ability to rotate your upper body at the shoulders. There will be times you need to reach for something beyond and just behind you, but the most important thing is that your arms and shoulders have unobstructed range of motion for the process of wheeling a manual chair.

Many current wheelchair designs allow the vertical support rails of the back of the chair to be set at various heights so that back height can be customized. The upholstery has the ability to adapt to the support heights, with any extra material folding back underneath or running along the seat pan beneath the cushion. It is then held in place with Velcro.

When you order your chair, you will usually specify a back height that is then adjustable within a range of a few inches. A third-party rigid back can be installed on the chair rails at the specific height desired. They also come in different vertical sizes.

One of the risks of using a wheelchair if you are not able to move your legs or experience significant spasticity is to have your foot fall off a footrest, or be improperly supported to begin with, and then be injured by getting caught on an object or literally run over by the chair itself. That’s especially dangerous for power chair users. To achieve good support for your feet while maximizing mobility, you’ll want to take care to choose the right footrests— including hanger angle, type of footplate, and type of supports—for you.

There are essentially two types of footrests—fixed and swingaway. Fixed footrests are increasingly common, spurred by the growth and popularity of rigid frame wheelchairs. They are integrated into the frame of the chair and are held in place by telescoping tubes that slide into the frame to be adjusted for your leg length.

A fixed footrest typically has a single metal plate that holds both feet, rather than a separate plate for each foot. The single footplate either attaches between two tubes that extend from the frame or is clamped onto a tube that is part of the frame itself. The single footplate is therefore a design that can add to the structural rigidity of the chair. And, since it involves fewer moving parts, there is less maintenance risk. For an example of a fixed footrest, see Figure 4-1.

Swingaway footrests are the historical norm and remain an option for most folding wheelchairs that would be specified for a regular user. Individual footplates are attached to the bottom of hangers—metal tubes that attach onto the frame structure. A spring release allows the hanger or footrest mechanism to be held in place but easily released to swing the whole unit aside or remove it completely. The ability to remove your footrests can help when sitting at a table with a large base, getting into a very small elevator, approaching a bathtub, or putting your chair into an automobile trunk. For an example of swingaway footrests, see Figure 4-2.

The footplates of swingaway footrests usually flip up to help you transfer to or from the chair. Flip-up plates are mandatory for folding chairs or the chair would be prevented from closing. (If someone else folds your chair, be sure they know the footplates have to be lifted first, to avoid damage to your chair.) Some folding chairs offer the option of a full-width plate that can also flip up as a single unit to allow the chair to fold. The single plate offers added structural stability—helping a folding chair to perform more like a rigid one—as well as more freedom for the positions of your feet.

As you wheel, your feet are kept from sliding off the footplates by heel loops—strips of sturdy material attached and looped across the rear of the footrests. Instead of heel loops, some chairs—usually rigid frame chairs with single footplates—use a support strap that passes across the frame behind the calves, keeping your feet in place by preventing your legs from sliding backward. Some people find their feet are less stable with a calf-support strap, particularly if they have a tight hanger angle. Feet can more easily slide off the footplate. Adjusting the footplate at more of an angle—or specifying an angle when you order the chair—can help.