A motion-preserving implant device for insertion between two bones is disclosed. The motion-preserving implant includes a first plate for engaging with a first bone and a second plate for engaging with a second bone. An articulation member is positioned between the two plates and a motion-controlling member attached to one or both of the plates. In some embodiments, the motion-controlling member is configured to constrain, dampen, and/or bumper the relative motion between the two plates.