Hepple et al 33 classification (MRI)
| Stage | Description |
| I | Articular cartilage injury |
| IIa | Cartilage injury with bony fracture and oedema (acute) |
| IIb | Cartilage injury with bony fracture and oedema (chronic) |
| III | Detached, non-displaced bony fragment with fluid rim beneath fragment |
| IV | Displaced fragment, uncovered subchondral bone |
| V | Subchondral cyst present |