Table 2 Weishaupt’s criteria for Facet joint degenerative class

Class 0

Normal facet joint space (2 ~ 4 mm width)

Class 1

Narrowing of the facet joint space (< 2 mm) and / or small osteophytes and / or mild hypertrophy of the articular process

Class 2

Narrowing of the facet joint space and / or moderate osteophytes and / or moderate hypertrophy of the articular process and / or mild subarticular bone erosions

Class 3

Narrowing of the facet joint space and / or large osteophytes and / or severe hypertrophy of the articular process and / or severe subarticular bone erosions and / or subchondral cysts