A study of pressure distributions measured during balanced and unbalanced sitting.

An instrument that measures pressures distribution during normal and unbalanced sitting was developed and tested. Analysis of the distribution of pressure during sitting in fifteen normal patients showed that approximately 18 per cent of the body weight is distributed over each ischial tuberosity; 21 per cent, over each thigh; and 5 per cent, over the sacrum. Three patients who had problems with sitting balance showed foci of unequal pressure which are at risk for decubitus ulceration.