Table 2.

The scoring system of the joints according to Koizumi et al. (Koizumi et al. 1999)

	Mild (grade 1)	Moderate (grade 2)	Sever (grade 3)
Synovial proliferation	3–4 layers of synoviocytes	5–7 layers	> 7 layers or papillae
Inflammation	occupying < one-third of × 200 field	Occupying one to two theirs of × 200 field	occupying > two-thirds of × 200 field
Degenerative changes of joint	Minor destruction of cartilage and subchondral bone	Clear loss of cartilage and involvement of 30% of underlying bone	Total loss of articular cartilage and involvement of > 30% of underlying bone