Study on an Onset Mechanism of MDRPU by Wearing Elastic Stockings: Numerical Simulation by Two-Dimensional Mechanical Model

As compared with pressure injuries, the mechanism the development of medical device related pressure ulcers (MDRPU) is not revealed enough. According to studies on severity and frequent site of occurrence, MDRPUs are surmised to occur the surface of the skin. In this study, we assess theoretical and experimental analysis by two-dimensional mechanical model for elastic stockings (ES) wear the lower limbs with or without dug into the skin by the wrinkles and curling up of ES. The Finite Element Method (FEM) was used to calculate the stress on the skin and subcutaneous tissue, because of elucidating the mechanism of MDRPU. The FEM used a triple-layered cylindrical model simulating the skin, subcutaneous tissue, and bone. Regarding the interface pressure (compression pressure), two samples were created: the one is applying a uniform pressure of 5.3 kPa on the skin surface simulating the correct wearing of ES, and the other is applying a pressure of 16 kPa on the part of the skin on which ES dug in. The results were as follows: the internal stress on the skin and subcutaneous tissue was maximum at the site where ES dug in, producing stresses of 54 kPa, 50 kPa, and 21 kPa in the circumferential, longitudinal, and radial directions, respectively. The uniform pressure produced an internal stress of 5–9 kPa on the skin surface. Unlike the mechanism of pressure injury formation, we considered compressive strength from tensile of the circumferential and longitudinal directions, furthermore the additive radial pressure at the digging site on the skin due to the wrinkles and curling of ES, which is one of the factor to cause strong external force in the MDRPU formation. (This is secondary publication from Jpn J Phlebol 2021; 32(1): 119–126.)