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.