A technique for harvesting bone graft material for spinal and other fusion surgeries. In the disclosed embodiment, a bone cutting blade is placed in a disc space between two vertebrae to be fused. The blade cuts into the vertebrae and forms solid segments of autologous bone inside each vertebra. Each bone segment is urged out of its associated vertebra until a first portion of the segment enters the opposite vertebra, an intermediate portion spans the disc space, and a second portion remains in the associated vertebra. Each segment thus forms a strut graft to promote a healthy and permanent fusion. In another embodiment, a wire is placed in the disc space and rotated to cut grooves in the vertebrae, causing a slurry of morselized cortical and cancellous bone to ooze into a cage that is placed in the disc space. The slurry heals to fuse the vertebrae solidly and permanently.