Parameter
Safranin O-fast green staining
0 = uniform staining throughout articular cartilage
1 = loss of staining in superficial zone of hyaline cartilage <50% of the length of the condyle or plateau
2 = loss of staining in superficial zone of hyaline cartilage >50% of the length of the condyle or plateau
3 = loss of staining in the upper 2/3’s of hyaline cartilage <50% of the length of the condyle or plateau
4 = loss of staining in the upper 2/3’s of hyaline cartilage >50% of the length of the condyle or plateau
5 = loss of staining in all of hyaline cartilage <50% of the length of the condyle or plateau
6 = loss of staining in all of hyaline cartilage >50% of the length of the condyle or plateau
Structure
0 = Normal
1 = Surface irregularities
2 = Fissures in <50% surface
3 = Fissures in >50% surface
4 = erosion 1/3 hyalin cartilage <50% surface
5 = erosion 1/3 hyalin cartilage >50% surface
6 = erosion 2/3 hyalin cartilage <50% surface
7 = erosion 2/3 hyalin cartilage >50% surface
8 = full depth erosion hyalin cartilage <50% surface
9 = full depth erosion hyalin cartilage >50% surface
10 = full depth erosion hyaline and calcified cartilage to the subchondral bone <50% surface
11 = full depth erosion hyaline and calcified cartilage to the subchondral bone >50% surface
Chondrocyte density
0 = No decrease in cells
1 = focal decrease in cells
2 = multifocal decrease in cells
3 = multifocal confluent decrease in cells
4 = diffuse decrease in cells
Cluster formation
0 = Normal
1 = <4 clusters
2 = >4 but <8 clusters
3 = >8 clusters