Computer simulations of efficacy of air-cell-based cushions in protecting against reoccurrence of pressure ulcers

Abstract

For individuals with a spinal cord injury (SCI) who depend on a wheelchair for mobility, sitting-acquired pressure ulcers (PUs) are a common and life-endangering complication. In the short time following an SCI, pathoanatomical and pathophysiological changes that affect the weight-bearing tissues of the buttocks may increase the risk for PUs, exposing this already-at-risk population to the additional potential risk caused by soft tissue scarring. In this work, we evaluated the biomechanical efficacies of an air-cell-based (ACB) cushion for individuals with SCI who have previously experienced PUs that healed but left scars in their soft tissues. We used 11 finite element model variants of the buttocks describing various scar shapes and severities to study the effects of the scars on soft tissue stresses during sitting on an ACB cushion and the resulting theoretical risk for the reoccurrence of PUs. Interestingly, the ACB cushion induced, in general, lower peak stress values in the soft tissues of the buttocks when scarring was present with respect to the stress levels in the (nonscarred) reference case. Our simulations therefore suggest that the ACB cushion is generally better protecting patients with a history of severe PUs manifested by large, possibly deep tissue scarring in their buttocks.

Keywords: deep tissue injury; finite element modeling; pressure ulcer; risk factors; scars; sitting biomechanics; spinal cord injury; support surfaces; wheelchair; wheelchair cushion.