Prone positioning is used for surgical access and recently in exponentially growing numbers of coronavirus disease 2019 patients who are ventilated prone. To reduce their facial pressure ulcer risk, prophylactic dressings can be used; however, the biomechanical efficacy of this intervention has not been studied yet. We, therefore, evaluated facial soft tissue exposures to sustained mechanical loads in a prone position, with versus without multi‐layered silicone foam dressings applied as tissue protectors at the forehead and chin. We used an anatomically realistic validated finite element model of an adult male head to determine the contribution of the dressings to the alleviation of the sustained tissue loads. The application of the dressings considerably relieved the tissue exposures to loading. Specifically, with respect to the forehead, the application of a dressing resulted in 52% and 71% reductions in soft tissue exposures to effective stresses and strain energy densities, respectively. Likewise, a chin dressing lowered the soft tissue exposures to stresses and strain energy densities by 78% and 92%, respectively. While the surgical context is clear and there is a solid, relevant need for biomechanical information regarding prophylaxis for the prone positions, the projected consequences of the coronavirus pandemic make the present work more relevant than ever before.

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Objective: Sitting-acquired pressure ulcers (PUs) are common in wheelchair users. These PUs are often serious and may involve deep tissue injury (DTI). Investigating the mechanical properties of the tissues susceptible to DTI may help in guiding the prevention and early detection of PUs. In this study, shear wave elastography (SWE) was used to measure the normative mechanical properties of the soft tissues of the buttocks, i.e. skeletal muscle and subcutaneous fat, under the ischial tuberosities, in a convenient sample of healthy adults without weight bearing and with weight bearing of different times. Approach: We compared the stiffness properties of these soft tissues between the lying prone and sitting postures, to determine whether there are detectable property changes that may be associated with the type of posture. We hypothesized that muscle contractions and 3D tissue configurations associated with the posture may influence the measured tissue stiffnesses. Main results: Our results have shown that indeed, SWE values differed significantly across postures, but not over time in a specific posture or for the right versus left sides of the body. Significance: We have therefore demonstrated that soft-tissue stiffness increases when sitting with weight bearing and may contribute to increasing the potential PU risk in sitting compared to lying prone, given the stiffer behavior of tissues observed in sitting postures.