A pressure reducing device for reducing pressure at bony prominences of limbs is disclosed. A preferred embodiment is formed of an elastic foam, having upper and lower portions similar to oppositely-facing square pyramids, but having four arced sides rather than flat sides, and where the four sides converge at their apexes to form a blunted peak. The cushion body is shaped and sized so as to reduce the loading and shearing forces over the bony prominences of limbs, thereby reducing pressure and to readily allow a user to move along the support surface and to change orientations (roll or lie on their side).