A BIPHASIC POROELASTIC ANALYSIS OF THE PLOW DEPENDENT SUBCUTANEOUS TISSUE PRESSURE AND COMPACTION DUE TO EPIDERMAL LOADINGS - ISSUES IN PRESSURE SORE

A layer of skin and subcutaneous tissue on a bony substratum was model ed as a homogeneous layer of biphasic poroelastic material with unifor m thickness. The epidermal surface and the bony interface were taken t o be impervious. The soft tissue on the bony interface was assumed eit her fully adhered or completely free to slide on the bone. The cases f or surface pressure loadings and displacement controlled indentations were simulated The resultant biomechanical responses of the layer, inc luding the transient tissue hydrostatic pressure and the tissue compac tion, were presented. A new hypothesis is offered to interpret the thr eshold pressure-time curve for pressure sores in term of the time requ ired for a particular area in the tissue layer to reach tr critical co mpaction for a given level of applied pressure.