Table 1 Brantigan fusion grading criteria

Grade 1

Unfused

Obvious radiographic Pseudarthrosis based on collapse of the construct, loss of disk height,vertebral slip,broken screws,cage displacement.

Grade 2

Probable unfused

Probable radiographic pseudarthrosis based on significant resorption of the bone graft, or a major lucency or gap visible in the fusion area.

Grade 3

Uncertain

Bone graft is visible in the fusion area at approximately the density originally achieved surgically. A small lucency or gap may be visible involving a portion of the fusion area with at least half of the graft area showing no lucency between the graft bone and vertebral bone.

Grade 4

Probable fused

Bone bridges the entire fusion area with at least the density originally achieved intraoperatively. No lucency between the donor bone and vertebral bone should be present.

Grade 5

Fused

The bone in the fusion area is radiographically denser and more mature than originally achieved intraoperatively. No lucency could be detected between the graft bone and cage with vertebral bone.