Grade | Description |
0 | Radiographic fusion: bone bridges at the fusion area with the density originally achieved at surgery. Radiographic fusion through one cage. |
1 | Radiographic fusion: bone bridges at less than half the fusion area close to the density originally achieved at surgery. Radiographic fusion through one cage (half of the fusion area with lucency < 1 mm on the opposite side). |
2 | Radiographic fusion: bone bridges at least half of the fusion area close to the density originally achieved at surgery. Radiographical fusion through one cage (half of the fusion area with lucency > 1 mm on the opposite side). |
3 | Radiographical locked nonunion indicated by lucency < 1 mm visible in the middle of the cages with solid bone growing into the cage from each vertebral endplate. |
4 | Radiographical locked nonunion indicated by lucency > 1 mm visible in the middle of the cages with solid bone growing into the cage from each vertebral endplate. |
5 | Significant resorption of the bone graft, or lucency visible around the periphery of the graft or cage. |
6 | Radiographical pseudarthrosis is indicated by collapse of the construct, loss of disc height, vertebral slip, broken screws, displacement of the carbon cage. |