Abstract: A system and methods for assembling an expandable vertebral implant for engagement between vertebrae. The implant may expand and/or collapse between a variety of lengths. The implant may include an inner core, an outer core, and/or a middle core such that the inner and outer cores may be moveable relative to each other along an axis. The middle core may include one or more gear teeth. The implant may include one or more locking mechanisms. The implant may include one or more endplates. One endplate may be fixed and/or polyaxial. A tool may be used to vary the length of the implant.