A surgical prosthetic implant for the vertebral column in the form of a rigid, preferably inert metal, plug having a porous metal surface allowing ingrowth of bone cells for biologic fixation is provided to achieve vertebral interbody fusion for treating or preventing back pain in patients with ruptured or degenerated vertebral discs. The plug forms a strut spanning and maintaining the disc space between adjoining vertebrae and has opposite ends bottomed in channels that are cut into the opposing faces of the vertebrae or opposed faces bottomed on the end faces of adjoining vertebrae. Bone ingrowth into the porous surface of the plug achieves long term biological fixation with living bone. Local bone graft harvested from the channel cuts into the vertebrae to receive the plug supplements the fusion. The implant minimizes or eliminates the need for bone graft material obtained from a second surgical site or from a bone bank and simplifies the method of achieving the interbody fusion.