Described here are deformable, monolithic, stabilization devices, or implants, suitable for use within bone and between bones, for instance, to fuse vertebral bodies, to repair herniated discs, or to repair spinal compression fractures. The implants are introduced into a chosen site at a first, smaller height and then plastically deformed to achieve a second, but unique, pre-selected, larger height. Variations of the device provide one or more specific larger heights. The devices are particularly suitable as intervertebral spinal fusion implants for the immobilization of adjacent vertebral bodies. Methods of deploying the implants are also described as are instruments for such deployment.Also described are variations of the device particularly suitable as sizing instruments. These versions are elastic, i.e., not plastically deformable, and may be restored to their original size. Many of the described variations include deformable regions serving as hinges. Other variations are non-monolithic or may have one or more classical hinges substituted for the deformable regions.