Described is an inflatable implant suitable for placement in the human body and left there for an indeterminate and potentially lengthy period of time. The implant is one that has a low profile when introduced into the body and a larger profile when it is inflated with one or more filler materials. Depending upon design and use choices the delivered implant may be removable and adjustable in situ in size, position, location, form, and rigidity. Indeed, in some variations, the design of the implant may be such that it may be removed at a potentially fairly lengthy time after implantation. The implant includes at least one bladder wall that generally is at least partially non-elastic (or unexpandable) after the preselected size is reached. The bladder wall will define at least one fillable volume and may form more than one independent fillable volumes. The bladder wall, in some variations, may be partially elastic or expandable to permit adjustment of implant size or configuration after or during delivery. The implant may be used as a supporting structure in a variety of differing body tissues and structures, e.g., in the spine or as a prosthetic in plastic surgery. The implant may also be used in conjunction with other components (often having a springed bias) as a source of movement in controlling the opening of a lumen or duct, that is to say, as a type of on-off valve or as a controlled flow valve. The implant may be used as an occludant within, or adjacent to, a variety of natural or abnormal anatomical body openings, e.g., vascular and genital lumina, aneurysms, ducts, septal defects, fistulae, esophagus, etc. The wall and filler material may be selected to deliver treatment materials the locale of the implant site or to remove amounts of harmful materials from such a region. The implant may, with an appropriate filler material or bladder wall material, be used in cooperation with an appropriate radio frequency (RF) source to cause the increase of a localized internal temperature and a resulting tissue change such as coagulation, ablation, or the like. Methods of using the implant are also described.