This procedure is used to relieve pain caused by damaged vertebrae bones that block or pinch nerve roots. It can also be used to correct spinal deformities. The space between the affected vertebrae is cleared and prepared to receive a bone graft. The vertebral space is then opened and any spinal curvature deformity is corrected or reduced. Finally a bone graft is inserted and a piece of metal is bolted onto the vertebrae to keep the area secure while the bone heals and forms a bone fusion.