Pressure Sores & Cushions


Considering that most wheelchairs are supplied without inbuilt cushioning, it is common sense that the most basic cushion will provide an improvement to comfort.

But a wheelchair cushion is also a pressure relieving device. Anyone in a wheelchair has reduced opportunity for movement, Pressure sores or ulcers may be caused and aggravated just by that simple fact of stillness, because able-bodied people move around or get up regularly if sitting.

Assessment of wheelchair seating

Assessment or grading of wheelchair seating needs to consider it's pressure-relieving properties.

We consider below, the probable causes of pressure sores or ulcers, and how these unwanted effects might be minimised. Once a pressure sore develops it is usually a task to get it healed.

Typical causes of pressure sores or ulcers

A pressure ulcer, also known as pressure sore, is a skin lesion (damage).

The skin lesion may be caused by

- unrelieved direct pressure on the skin which could reduce blood flow

- by shearing, such as when sliding into or out of a wheelchair

- or by friction forces on the skin tissue, perhaps when the user propels themselves about by using their hands on the wheels.

The possible causes are therefore at least three-fold, although pressure and shearing may be the most important factors for people in a sitting posture.

And especially if someone is paraplegic (so cannot feel sensation below the waist), damage to skin may occur and not be felt.

We consider below each of the factors:


Study has shown that 50% (1/2) of the body’s weight when sitting, is supported by only 8% (1/12) of the sitting area between body and seat.

Therefore we often do not find long term sitting very comfortble, -even if fit - merely because the bony parts of our sitting apparatus take the brunt of the weight.

So sitting means that the 8% area is indeed under stress. The weight is taken (unless we have extra natural padding!) by two 'ischial tuberosities', the bony prominences of our pelvis. Further, poor seat design may mean that the coccyx (the base of the spine, or tailbone or sacrum) also receives pressure.

Consequently, there is a high load pressure on only a smallish area, the underlying tissue in this region may become ischaemic (lack of blood circulation) and (if you sit for days at a time!) necrotic (cell death). This damage under the skin may surface eventually as a wound, and persist unless the pressure is relieved and healing occurs.

So taking care to relieve or redistribute long term pressure is a must for wheelchair users.


Under the action of shearing (sideways) forces the bony prominences mentioned above must slide inside the surrounding skin. This can be an invitation for eventual formation of pressure ulcers

Pressure ulcers are often preventable, but given that a normal healthy body needs to re-adjust itself at frequent intervals at the first signs of pressure discomfort, the nursing job of an “at risk” person can be demanding and persistent since if they cannot move themselves in the seat, it must be done for them. Accordingly, the assistance of an appropriate cushion becomes a major tool in the care management task.

The need to have a broader view

Although the above highlights the major causes of pressure ulcers derived from sitting postures, the analysis is rather simplistic. In the past, attempts were made to to classify cushions relative to 'risk assessment scales' (e.g. Waterlow, Norton).

But in actuality the risk assessment needs to be more holistic (broad in scope) and be related to overall clinical management embracing the wider issues of concurrent diseases, medication, nutrition, physique and other features unique to the wheelchair-bound person.

Cushion Classifications

All cushions will make a contribution to the foremost task of spreading and redistributing pressure away from the bony prominences to a larger area - and at the same time cushions need to provide postural stability without causing the user to slide down in the chair.

The degree to which the cushion achieves the above aims determines its classification into the current U.K National Health Service classification of low-technology and high-technology cushions.

How Glanmor rates its cushion products

With reference to this NHS standard the Glanmor range of cushions is classified as follows in increasing order of pressure reduction and seating stability.

The 'Low-tech' Cushion

- Foam filled Cushion
- Fibre filled Cushion

- Natural Sheepskin pad

- Natural sheepskin covered foam filled cushion

- Gel pad

- Gel & foam filled cushion

The High-tech Cushion

- Air filled Sac

Manufacturing methods of wheelchair cushions

Beneficial factors such as two way stretch coverings, internal wall partitioning, waterproof vapour permeable coverings, are also important features of the different cushion designs.

Flame retardant qualities of wheelchair cushions

All cushions are flame retardant to the following standards -

Sheepskin & sheepskin-based cushions meet the requirements of BS7176:1995 Medium Hazard Category when tested using BS5852:1990 Ignition Source 5 (Wooden Crib)

Foam cushions with PU coated waterproof cover meets the requirements of BS7176:1995 Medium Hazard Category when tested using BS5852:1990 Ignition Source 5 (Wooden Crib)

Gel cushions with PU coated waterproof covers and with or without foam meet the requirements of BS7176:1995 Low Hazard Category when tested using BS EN 1021-2:1994 (Match Flame Equivalent)

Air Cell Cushions meet the requirements of BS7176:1995 Low Hazard Category when tested using BS EN 1021-1:1994 (Smoulder Cigarette)

Quality of wheelchair cushions

All cushions are CE marked as compliant to the Medical Devices Directive 93/42/EEC