US Patent 7441290 Mattress hinges to provide greater stability and lower shear

A rotational mattress has (a) a support surface and a rotating bladder object or (b) the support surface, the rotating bladder and a cushion material object. Depending on the embodiment used, the rotating bladder object and/or cushion material object has at least one longitudinal hinge; a longitudinal hinge extends from the object's head end toward the object's foot end. In one embodiment, the longitudinal hinge can be a shaped aperture and within the shaped aperture is a second cushion material. The second cushion material is less rigid than the cushion material.