An expandable spinal interbody implant having a base member and a displaceable member connected by a screw driven linkage mechanism. The implant may include mechanisms for controlling the implant throughout its full range of expansion and retraction to prevent formation of the implant into undesired profiles in the intervertebral space. The displaceable element may be overlapped with the base in a fully expanded state. Alternatively, the displaceable element may exist fully outside of the base. The displaceable element may be hinged and bent in conjunction with the linkage based implant expansion.