Abstract
Shear deformation is known as one of the mechanical factors which applies on the skin surface and causes a pressure ulcer in soft tissues in bony prominence regions. We conducted a shear test on the skin surface of soft tissues which was obtained from porcine hind feet and examined the mechanical properties and deformation behavior of subcutaneous tissue. We also examined the microscopic structure of the soft tissues including subcutaneous tissue using techniques of Masson trichrome stain and X-ray computed tomography. In addition, we applied a standard linear solid model, one of one-dimensional linear viscoelastic models, to the results of the shear loading test on the subcutaneous tissue, and identified the parameters of elasticity and viscosity. Using a microscopy for the stained specimen, we observed thin layers of collagen fibers and a large amount of adipocytes in the subcutaneous tissue. In the shear loading test, we found “sliding deformation” or a large amount of shear deformation in a thin layer in the subcutaneous tissue and the regions between the subcutaneous tissue and the adjacent tissues. We speculated that the layers of loosely-bonded collagen fibers with elastic fibers which were embedded in the adipose tissue may be the cause of such deformation.
