Types of Wheelchair cushions
Foam cushions
Foam technology has come a long way. No longer just the soft, airy stuff of the past, foam now comes in a range of densities and with varying degrees of “memory,” holding its shape as you sit, contributing to your stability. The new foams can adapt to any shape, and still provide even support, spreading pressure across the sitting surface. Different foams are often used in combination, layered for their various properties of softness, even support, and memory.
Foam is relatively inexpensive, and it is easy to cut. A therapist can experiment with shapes free of financial risk. If you have an area of skin that is broken down or on the verge, pressure can easily be reduced by cutting out a portion of the cushion. (You should not do this on your own, though, because only a doctor or therapist can identify the changes in your cushion that will help relieve pressure while still maintaining appropriate support.)
On the downside, foam wears out faster than other materials and loses its shape, but because of its lower price, this might not concern you. If you choose a foam cushion, be sure to replace it when its time is up. Old foam that is compressed can allow pressure points to form that can lead to a sore.
Gel cushions
Gel cushion designs attempt, in effect, to replace the consistency and support of atrophied muscle tissue. Highly engineered gel fluids are placed in pouches and usually attached to a foam base, so that the cushion conforms to the pressures placed on it. As a result, gel cushions provide excellent pressure distribution and are very comfortable. Many gel products also offer supplemental inserts to stabilize your legs. Your knees might tend to fall together (adduction) or apart (abduction), so such an accessory can help keep your legs straight which also aids your overall posture.
Unfortunately, gel cushions are much heavier than other types, which can cancel out some of the benefits of your lightweight wheelchair. Gel suppliers such as Jay and Flofit offer lighter, active-use designs, but these might not be appropriate for you if you are unable to do your own pressure-relief lifts.
If you bounce up and down curbs, or commonly experience similar impact in your chair, a gel cushion might not be ideal. When you sit in a gel cushion, there is no further “cushiness” to absorb impact, a concept known as impact loading. Other cushion types are better able to absorb impact.
Another drawback to gel cushions is the possibility of them “bottoming-out” as the gel is pushed aside by your weight. You can help prevent this distribution problem by kneading your gel cushion once a day, keeping the fluids loose and spread evenly. Look for a design that divides the gel portion into several sections so that all of the gel cannot push to the sides.
There is also the chance of the gel leaking. While cushions arrive with patching kits, patches are ineffective when the breach is at a seam, which is often the case. A leak might be very minor, or it could be an extremely messy affair.
Air or dry flotation cushions
Air flotation cushions support the body entirely on air. A typical example is the Roho cushion, designed with a group of small, interconnected rubber balloons arranged in rows. Pressure is balanced by air shifting out to surrounding balloons, spreading pressure evenly against your skin. The whole system is closed so air flotation cushions can’t bottom out the way gel cushions can.
If you have a pressure sore, you can tie off individual balloons to reduce contact under that area, allowing you to spend more time sitting as the sore heals. The Roho Quadtro allows the user to inflate four quadrants separately for optimal positioning. Air cushions are relatively lightweight, and are waterproof, allowing for double duty in the bathtub or on a boat.
Crown Therapeutics, maker of the Roho cushions, also offers air floatation products for the wheelchair back, supplemental lumbar or sacral support, full bed cushions, and even a product for a standard toilet seat. All are inflatable to adjust to your needs.
A longtime presence in disability magazines has been an ad for the “Bye-Bye Decubiti” cushion. It is inflatable, comes in many different sizes and shapes, is made of heavy duty rubber, and–although different from the Roho balloon design–is uniquely formed to minimize pressure at the bony protrusions on which we sit.
Air cushions can be less stable for those who move around a lot in their chair, but recent designs offer either low profile or quadrant options that minimize this problem. The balloons used in air cushions can be punctured, of course, and leaks do occur, although a fairly heavy duty rubber is used. But patching them is easier than with the gel design. The hard part is submerging the cushion under water to find the leak (look for escaping air bubbles).
The biggest drawback to air cushions is that they require more maintenance. It is necessary to check the pressure frequently, especially if you have pressure sores.
Urethane honeycomb cushions
Thermoplastic urethane honeycomb cushions are the most recent development in the world of cushions. Because there are many individual cells–like a beehive–these cushions are able to distribute weight evenly, but there is no risk of leaking gel or of an air bladder being punctured. The many open spaces in the beehive structure of the cushion allow air to travel more effectively. This design helps to protect against skin breakdown because your skin is kept cooler and moisture is prevented from collecting.
Urethane honeycomb cushions are very light, absorb shock, and a low profile cushion can provide significant support. These cushions can even be thrown into your washing machine and dryer, making them attractive for people with incontinence problems where the cushion will be soiled from time to time despite best efforts at bowel and bladder management.
Supracor of San Jose, California, makes several honeycomb cushions based on their patent. One type uses multiple layers of varying stiffness to allow your sit bones to sink into the cushion while deeper layers provide overall support and weight distribution. Another type is contoured to provide adduction and abduction, plus a rear dish for pelvic positioning. There is not much of a track record for urethane honeycomb cushions because of their recent development, but there appears to be good prospects for this type of cushion to evolve and become more widely used.
By Maricon Williams