Microstructural characteristics of human skin subjected to static versus cyclic pressures

Pressure ulcers are generally associated with external pressures exceeding internal capillary pressures over bony prominences when the body cannot ini tiate motor movement to change positions. This investigation evaluated micr ostructural changes occurring in human skin, in vitro, exposed to static ve rsus cyclic pressures, simulating those recorded for heels of human subject s on various pressure-relief mattresses. Morphological data are reported fo r tissues exposed to pressure in a bench-scale loading system. Dynamic (cyc lic-relief) pressure induced parallel alignments of connective tissue colla gen bundles, which themselves became differentially oriented to various deg rees perpendicular to the surface of the tissue. Static pressure, with no r elief, invariably produced alignment of the collagen bundles of the connect ive tissue parallel to both one another and to the compressed tissue surfac e. The precursor to pressure ulcer formation may be microstructural alignme nt in response to the pressure conditions on tissue.