An implant for treating medical disorders includes a first chamber having a flexible outer layer that surrounds a flexible inner layer, a second chamber in communication with the first chamber, and a fluid transfer assembly adapted for transferring fluid between the second chamber and the first chamber for selectively modifying the rigidity of the first chamber. The implant includes at least one restraining element in contact with the flexible outer and inner layers for at least partially restricting volume expansion of the first chamber as the fluid is transferred into the first chamber. The first chamber is adapted to become more rigid as the fluid is transferred into the first chamber and more flexible as the fluid is removed from the first chamber. The first chamber is implantable within the soft tissue of a patient such as a tongue, soft palate, pharyngeal wall, urinary tract, rectum, trachea, or stomach.
