Figure 4.

Degenerative changes of zygapophyseal joints (indicated by red arrows). Grade 0: the normal condition. Grade I: osteophytes grew on the rim of articular surface without pitting on the surface; Grade II: osteophytes grew on the rim of articular surface with lipping with slight pitting; Grade III: osteophytes grew all around the rim of the articular surface with moderate pitting on the surface and the rims of articular surface; Grade IV: osteophytes grew on the rim of articular surface with severe pitting on the surface.