Wheelchair cushions are cushions specifically designed to provide comfort and protection against injury for

wheelchair A wheelchair is a chair with wheels, used when walking is difficult or impossible due to illness, injury, problems related to old age, or disability. These can include spinal cord injuries ( paraplegia, hemiplegia, and quadriplegia), cerebr ...

users. They also aid in properly positioning the user in the correct posture. Wheelchair users are at great risk for

pressure sore Pressure ulcers, also known as pressure sores, bed sores or pressure injuries, are localised damage to the skin and/or underlying tissue that usually occur over a bony prominence as a result of usually long-term pressure, or pressure in combi ...

s. A number of factors are included in the formation of these ulcers including: # Insufficient vascularization in areas of high pressure, typically under bony prominences. # The collection of sweat on the skin due to inadequate air flow. # The presence of local areas of elevated temperature. #

Shear stress Shear stress, often denoted by (Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the ...

es on the skin. A number of studies point to interface pressure between the body and the seating surface as the primary contributor to the formation of pressure sores. In response, manufacturers have developed a number of wheelchair seat cushion alternatives. Over 200 models of wheelchair cushions were on the market as of 2001.

Characteristics

Various characteristics, combined with a number of cover material options, offer a myriad of possibilities, which can be manipulated to provide various performance properties. These properties are intended to provide the wheelchair user optimal comfort, stability, and postural support, as well as aid in the prevention of pressure ulcers. The effectiveness of a particular choice of material and design has high variance with respect to a user's medical needs and activities. For instance, if a wheelchair user frequently moves on rough surfaces, gel cushions are less optimal as they are not as effective at absorbing impact. Sprigle et al. proposed the following criteria for defining and describing cushion characteristics: ;Material and construction * Cushions using cellular materials –

foam Foams are materials formed by trapping pockets of gas in a liquid or solid. A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the ...

(convoluted, segmented), flexible matrix,

viscoelastic foam Memory foam consists mainly of polyurethane with additional chemicals that increase its viscosity and density. It is often referred to as "viscoelastic" polyurethane foam, or low-resilience polyurethane foam (LRPu). The foam bubbles or ‘cells’ ...

or matrix, nondeforming foam or matrix * Cushions containing fluid – viscoelastic fluid, air cushion, water cushion * Other construction – solid elastomer and solid gel, cushion with displacing solid elements ;Physical characteristics * Surface characteristics – unloaded contour depth, loaded contour depth, contour, cut-out, segmented, convoluted foam * Features – preischial support, lateral

pelvic The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The p ...

support, medial thigh support, lateral thigh support * Other – bonded, compartment or chamber, stiffness, flat or curved base

Design examples

References

{{reflist Wheelchairs