A patient support apparatus includes a deck, a support structure supported on the deck, and a control system. The deck includes a head deck section and a seat deck section. The head deck section is movable between a lowered position and a raised position. The support structure is supported on the deck and includes a variable-shape cushion that is selectively configurable to a plurality of shapes. The control system coordinates configuration of the variable-shape cushion with movement of the head deck section such that movement of the head deck section upwardly causes the variable-shape cushion to be configured to resist shifting of a patients buttocks
