Polyurethane foam wheelchair cushions: retention of supportive properties.

The supportive properties of polyurethane foam wheelchair cushions change significantly during the first hours of use. Thus, cushions which initially appear to optimally distribute the patient's weight may not do so after a break-in period. To solve this problem, a cushion prestressing protocol has been devised which breaks-in the foam cushion prior to determination of the patient's pressure distribution. It was found that the useful life of these cushions is adversely affected by heavy static loading and high temperatures, and if allowed to rest, polyurethane foam cushions recover a portion of their original load-bearing properties.