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.