Arthrodesis is the fusion of vertebrae over a joint space that occurs through a natural process or as a result of surgical procedure. In surgery, arthrodesis, or fusion between two vertebrae, can be achieved by placing bone graft and/or bone graft substitute to bridge the vertebrae so that new bone grows into the spaces.

Arthrodesis immobilizes the joints at the level of the fusion. Thus, the procedure can be used to treat pain caused by the motion or instability of the spine.