The Critical Characteristics of a Good Wheelchair Cushion

Abstract

In this chapter, the authors describe the key characteristics of effective wheelchair cushions. The novel use of finite element (FE) computational modeling is introduced, aimed at examining the efficacy of various wheelchair cushion designs and their ability to protect patients against sitting-acquired pressure ulcers (PUs) and deep tissue injuries (DTI). Fifty-four FE model variants describing a reference spinal cord injury (SCI) anatomy with the addition of pathoanatomical changes associated with SCI (e.g. considerable weight gain, muscular atrophy, scars in the soft tissues) were developed and simulated sitting on a flat foam cushion, a contoured foam cushion or an air-cell-based cushion. Sufficient immersion and envelopment of the body were identified as key factors, which together represent the potential cushioning performance of a cushion, through minimization of internal tissue deformations, strains and stresses. A good wheelchair cushion should be able to accommodate the seated buttocks while providing the appropriate immersion and envelopment, during the entire time of intended use. Adjustability is another key factor, as the cushion has to be able to accommodate changes in posture and weight shifts associated with daily living, and conform to the remarkable disuse-related anatomical and physiological changes, which are expected in the months and years following a SCI. Furthermore, the cushion should maintain its physical and mechanical properties as well as its performance over time and despite exposure to various degenerating conditions, which can be expected during the lifespan of a wheelchair cushion. Given the recent advancements in understanding the aetiology of PUs and the availability of novel tools and research methodologies to assess wheelchair cushion efficacies, there is still a considerable gap between public policy and the current practice in cushion evaluation, and the challenges and measures that should be applied.