An apparatus for performing Trendelenburg therapy and reverse Trendelenburg therapy (22) includes an intermediate frame (52) carried above a base frame (25) by an inner cross-riser (64) pivotally connected to an outer cross-riser (80). One end of the outer cross-riser (80) is pivotally connected to the base frame (24), and the opposite end of the outer cross-riser (80) is rotatably and translatably connected to the intermediate frame (52) via a cam (56) and cam follower (118) arrangement in which the cam follower (118) rides on a wear plate (58). One end of the inner cross-riser (64) is pivotally connected to the intermediate frame (52), and the opposite end of the inner cross-riser (64) is both rotatably and translatably connected to the base frame (24) via a cam (44) and cam follower (78) arrangement in which the follower (78) rolls against a lower wear plate (46). A pivotable Trendelenburg linkage (86) is carried on the end of the inner cross-riser (64) connected to the intermediate frame (52), and a pivotable reverse Trendelenburg linkage (102) is carried on the end of the outer cross-riser (80) rotatably and translatably connected to the intermediate frame (52).