A patient positioning system for use with a patient on a bed includes a sheethaving a bottomsurface configured to be placed above the supporting surface of the bed and atop surfaceopposite the bottom surface, and a wedge having a base wall, a ramp surface,and a backwall, with the ramp surface joined to the base wall to form an apex. The wedgeis positionedunder the sheet such that the base wall confronts the supporting surface ofthe bed and theramp surface confronts the bottom surface of the sheet. The bottom surface ofthe sheet andthe ramp surface of the wedge have engagement members forming a selectiveglidingassembly that resists movement of the sheet with respect to the wedge in atleast one directionand permits movement of the sheet with respect to the wedge in at least oneother direction.
