| Grade | Definition |
|---|---|
| Stage 1 | Normal skin, continous erythema |
| Stage 2 | Superficial ulcer extended to dermis vesicle, damaged skin, well margined small ulcer |
| Stage 3 | Dermis, subcutaneous fat layer damaged but fascia undamaged severe undermining under skin layer possible |
| Stage 4 | Bone, muscle, ligament, articular capsule exposed sinus tracts may exist between erosion and ulcer |