The Gravity of Wheelchair Cushions

Your wheelchair cushion is your first line of defense against skin breakdown.

By Dr. Richard Louis Bruno

Those who wheel instead of walk have a special enemy: Gravity. And where does this enemy exert its particularly pernicious pull? It’s through the gluteal muscles (if you have some) and the ischial bones of the pelvis, that is, your butt. And your first line of defense against gravity? The seat cushion.

Much of the information in this article is available at United Spinal Association’s USA Tech Guide (www.usatechguide.org/cushion_reviews.php), a great source if you’re in the market for any assistive technology device.

Force and Friction

The job of a seat cushion is to provide a stable base of support and to prevent skin breakdown (decubitus ulcers) while gravity forces you downward onto the cushion, cuts off blood fl ow to your skin and rubs away thin skin that has little muscle to pad it. Cushions are made with a variety of materials, some of which can both support and prevent breakdown.

First are the basic single-piece covered foams cushions (Invacare Single Density, Jay Combi, TEMPUR Med) that are best for those without breakdowns. Then, there are cushions containing sacks filled with fluids and gels (Trulife, Jay Mobility) and combination foam/air cushions (Keen Mobility, Varilite) and foam/air/gel cushions (Pride Mobility Spectrum) that are helpful for those prone to breakdowns. There’s even a cushion for those who have a breakdown that needs to heal (Span-America Isch-Dish).

Other cushions have many foam inserts of varying hardness, or air bladders that allow the height of different areas of the cushions to be adjusted to compensate for a breakdown, to help those with scoliosis that causes one butt cheek to be higher than the other; for those who have atrophy that causes one cheek to be smaller, causing them to tip to one side. Foam and even gels are often not soft enough to cushion an unpadded bum. What may be needed are air-filled cushions that gives you gentle support as they distribute weight away evenly. The Bye-Bye Decubiti is an inflatable pillow, while Roho and Star cushions have rows of air- filled bananas intended to evenly distribute your weight. Instead of having many identical air-filled cylinders, Aquila’s new Custom Air Cushion has 18 compartments, long and flat in front to support the thighs, and wedge-shaped or round in back to support the butt. Some of these cushions fill all compartments with the same amount of air, while others allow the front and back halves, each quarter, or separate compartments to be filled with different amounts of air, allowing you to raise up some portions and lower others.

Regardless of what may look good (and cheap) on the Internet, the only way to know if a cushion works for you is find a local vendor and try it for a few days. Before the test run, make sure your footrests are at the correct height and angle so that you have proper posture above your butt, since it’s important that not only your keister is properly cushioned, but that your back is as well.

Cushions: Not Just for Pains in the Butt

Many wheelers think that they need only a butt cushion. But, once you find a cushion that tenderly cradles your derrière, you have to support the rest of you. Most of our patients don’t complain about butt pain or even skin breakdown. They report severe back, neck, and headache pain that have three causes that are highlighted below.

Muscle Imbalances

Imbalances occur when the muscles on one side of the body are weaker than on the other. In those with scoliosis, the spine is pulled to one side because the muscles on the other side are too weak to keep the spine straight. If the spine is pulled to the left, a curve is created that makes the upper body tilt to the right. Back and neck muscles on the weak side are overused and spasm as they push up in an attempt to appear level.

Substitution and Overuse

Many people with disabilities have learned to substitute stronger muscles for weaker ones. Quads with forearm weakness often substitute and overuse their shoulder and upper back muscles to move their hands, which can cause chronic muscle spasms.

Spasticity, Increased Tone, and Rigidity

In those with spinal cord injury and multiple sclerosis, the brain is disconnected from the spine and unable to tell muscles to turn off. When left to their own devices, spinal motor neurons do what they’re supposed to do: make muscles contract. This causes spasticity, where a muscle contracts to stop a muscle from moving. In cerebral palsy and after a stroke, the brain areas that tell muscles to turn off may be damaged, producing a continuous increase in muscle tone that causes continuously painful muscles. Muscle tone also increases with emotional stress, producing the well-known “muscle tension headache.”

Painless Posture

To control these causes of muscle pain, you need to develop painless posture using back and seat cushions to turn off offending spasms.

The first step to stopping muscle pain and preventing skin breakdown is to notice how you’re sitting while reading this. Are you slumped with head drooping forward, upper back curved and shoulders humped? Are you sitting with your back away from the chair, tilting your head or body to one side, leaning on your arm rests or sitting with your shoulders up around your ears?

If you are slumping, drooping or tilting, your back and neck muscles spasm as they try to resist the pull of gravity to prevent your body from toppling forward or to one side or when you overuse your arm and neck muscles. That’s why power wheelchairs are far superior to scooters when it comes to developing painless posture. (Please see this month’s Polio Tips and Techniques.)

Painless posture allows gravity to pull through the center of your body so that you don’t need muscles to keep you off the floor. Sit with your knees and hips bent at a 90 degree angle and your feet directly under your knees, your butt against the back of the chair and make sure that you have a lumbar lordosis, a slight curve in your low back just above your belt line. The sling back that comes with wheelchairs actually makes you slump and droop, so you need a lumbar cushion placed in the small of your back to straighten your upper back so that gravity is pulling through the center of your body. Even better, replace your sling back with a rigid back (Jay 2) with adjustable cushioning for just the right amount of lumbar curve. If you have weak trunk muscles or scoliosis, get a rigid back that can be custom fitted to hold your body up even if your muscles can’t. If you have upper back or neck pain, you may find a shoulder-high or head-high rigid back-or even a headrest-will allow your muscles to relax.

Is finding the right cushions, fixing your posture and stopping skin breakdown and muscle spasm pain that easy? If only! Since you’ve probably been sitting slumped and tilted for decades, it will take weeks of constant attention to the way you’re sitting-and actually have to feel uncomfortable-to know you’re developing painless posture. But your butt and your back will thank you for the effort!

Dr. Richard Louis Bruno, director for The Post-Polio Institute at Englewood (NJ) Hospital and Medical Center at PostPolioInfo.com, writes Action’s Polio Tips and Techniques column.