Table 1 Classification of HO following CDR
Grade | Definition |
|---|---|
0 | No HO was observed |
1 | HO does not occur within the disc space |
2 | HO is present between the planes formed by the vertebral endplates but does not block spinal motion |
3 | The range of motion of the vertebral endplates is blocked by the formation of HO or osteophytes |
4 | HO causes bony fusion |