An expandable implant device for implantation at a surgical site is provided. The implant device is made of cortical bone and includes a top and bottom piece, both pieces configured to couple with each other. The top piece has superior and inferior surfaces, and at least a tapered leading end configured to distract open an intervertebral disc space so that the top piece can be slidably inserted over the bottom piece until a desired overlap is achieved. A composite interbody bone implant device is also provided including a body skeleton having a non-bone composition, such as a polymer, formed into a shape and including one or more cavities which can be filled with other material, for example, allograft material. A method of placing an expandable device into a disc space is also provided.
