A spinal bone graft includes one or more cortical bone portions forming a first unit. The first unit includes an engagement surface for contacting bone, and a mating surface. The mating surface forms at least one first undercut. The bone graft also includes one or more cortical bone portions forming a second unit. The second unit includes an engagement surface for contacting bone, and a mating surface. The mating surface forms either at least one second undercut, or at least one connector. In the former, at least one connector is received in each of the first and second undercuts to interconnect the first and second units. In the latter, the at least one connector of the second unit is received in the first undercut of the first unit to interconnect the first unit and second unit.
