Table 1 The Mankin rating scale

I cartilage structure

 Even surface

1

 Uneven surface

2

 Fibrillated and fissured within superficial zone only

3

 Fissures and erosions extending below the surface zone, without extending beyond the radial zone

4

 Fissures and erosions extending into the deeper zone

5

II chondrocyte loss

 Loss extending into superficial zone

1

 Loss extending into midzone

2

 Loss extending into radial zone

3

III matrix distribution

 Normal staining

1

 Moderate loss in staining

2

 Severe loss in staining

3

 No staining

4

IV chondrocyte cloning

 No clusters

1

 Chondrocyte clusters in superficial zone

2

 Chondrocyte clusters in superficial to midzone (less than four cells)

3

 Chondrocyte clusters of more than four cells located in superficial to midzone, or chondrocyte clusters in deeper zone

4