An expandable intervertebral implant includes a bone graft implant dimensioned for insertion within an intervertebral space defined between adjacent vertebrae, able to vertically elevate and expand a plurality of ribs into the surrounding bone. The expandable intervertebral implant has a tubular outer body portion having a cylindrical axial bore with a triangular or elliptical cross-section and a plurality of ribs disposed on its outer body dimensioned to fit snugly within the space and an expansion cylinder with a triangular or elliptical cross-section slidably mounted within the axial bore of the tubular outer body. The tubular outer body portion of the expandable intervertebral implant permits the expansion and retraction of the ribs into or out of the surrounding bone as the expansion cylinder rotates.