| | Outerbridge | Collins | SFA |
|---|
| 0 | Normal Cartilage | Normal Cartilage | Normal Cartilage |
|---|
| S | Not applicable | Softening Cartilage | Not applicable |
|---|
| 1 | Softening and swelling of cartilage | Destruction of superficial cartilage, confined to areas of greatest press & movement – tangential flaking, early fibrillation, shallow pits or grooves | Swelling and/or softening |
|---|
| 2 | Fragmentation and fissuring in an area ½ inch or less in diameter | More extensive destruction of cartilage still confined to areas of pressure and movement but not denuding bone. Deep fibrillation and significant loss of cartilage substance | Superficial fibrillation |
|---|
| 3 | Fragmentation and fissuring in an area ½ inch or more in diameter | Total loss of cartilage in one or more areas of pressure with exposure and usually, eburnation of bone. Widespread fibrillation and flaking of the remaining cartilage. Areas of unaffected cartilage in those parts less exposed to pressure and movement | Deep fibrillation down to bone |
|---|
| 4 | Erosion of cartilage down to bone | Complete loss of cartilage from large areas of the joint surface. Eburnation of exposed bone | Exposure of subchondral bone |
|---|
