Biomechanical Analysis of a Serious Pressure Ulcer Case in a Real-World Scenario

Deep tissue injury (DTI) is a serious pressure ulcer, characterized by necrotic tissue mass under intact skin. There is evidence that elevated tissue strains/stresses over prolonged times cause DTI, via paths of physical damage to cells, ischemia and impaired diffusion. Skeletal muscle is considered less tolerable to mechanical loads, likely because of higher metabolic demand and denser vascularization. When damaged in compression, muscle tissue stiffens up to ∼3-fold, depending on the magnitude and duration of loading [1]. Cell-death thresholds for loaded muscle, that are a Boltzmann-type downward-step sigmoid function of the magnitude of compression strain/stress and time, were developed based on meta-analysis of animal experiments [2]. These cell-death thresholds allow extrapolation of biological damage trends from computational stress analyses of muscle in load bearing postures.