A beam acts as an implantable spinal support structure. The beam is generally cylindrical in form with two semi-cylindrical shells defining a cylindrical contour of the beam and with a web passing through a central axis of the beam and joining midpoints of the two shells together. The shells preferably have threads on an outer surface thereof to engage bone within a cylindrical hole passing through two adjacent vertebrae spanning a disk space, for support of the vertebrae such as for fusion thereof together. One end of the beam can be tapered to maximize structural support for the vertebrae. This tapered end can be provided as a separate extension removably attachable to other portions of the beam in one embodiment. A method for implantation is also disclosed where the beam is implanted at an angle to the spinal axis and intersecting a disk space between adjacent vertebrae.
