Effect of externally applied skin surface forces on tissue vasculature.

The effect of surface forces on the morphologic pattern of skin capillaries was examined on the anterior surface of the forearm of healthy volunteers. A rig was designed to permit the application of uniaxial forces between two pads attached to the skin surface. A grid was printed onto the skin surface, and mechanical data are presented in terms of force intensity versus strain. During force application the skin capillaries were monitored using vital capillary microscopy. Mean values of force intensity and strain of 1.33N/mm and 10%, respectively, were sufficient to produce virtual obliteration of the blood flow to the capillaries. A simplified finite element model of the tissue was also employed to illustrate the effect of surface forces at different depths within the tissue. This study emphasizes the potentially damaging effects of surface forces on the integrity of the skin vasculature. If these forces are maintained or repeated, cell necrosis and eventual tissue damage would result.