An articulated patient support apparatus includes upper and lower body support frames hinged together to form a patient support assembly which is hinged to head and foot end supports. One end of the assembly includes a length compensator to enable hinged angulation between the body support frames. Hinge motors are connected between the frames to cause hinged articulation therebetween. One or both of the body support frames has a body slide assembly mounted thereon to enable part of a patient's body to move linearly along the particular body support frame by operation of a slide motor to compensate for hinged articulation of the frames. The hinge motors and slide motor have encoders interfaced to a controller to digitally coordinate sliding movement with hinging articulation.