An improved ceramic bone graft is provided for human implantation, particularly such as a spinal fusion cage (10) for implantation into the intervertebral space between two adjacent vertebrae. The improved spinal fusion cage (10) includes a substrate block of high strength ceramic having a selected size and shape to fit the anatomical space, and a controlled porosity analogous to natural bone. The substrate block is coated with a bio-active surface coating material such as hydroxyapatite or a calcium phosphate to promote bone ingrowth and fusion. Upon implantation, the fusion cage (10) provides a spacer element having a desired combination of mechanical strength together with osteoconductivity and osteoinductivity to promote bone ingrowth and fusion, as well as radiolucency for facilitated post-operative monitoring. The fusion cage (10) may additionally carry one or more natural or synthetic therapeutic agents for further promoting bone ingrowth and fusion.
