Arnold-Hilgartner classification of haemophilic arthropathy

Arnold-Hilgartner classification is a plain radiograph grading system for haemophilic arthropathy of the knee ^1,2:

• stage 0: normal joint
• stage I: no skeletal abnormalities, soft-tissue swelling is present
• stage II: osteoporosis and overgrowth of the epiphysis, no cysts, no narrowing of the cartilage space
• stage III: early subchondral bone cysts, squaring of the patella, widened notch of the distal femur or humerus, preservation of the cartilage space
• stage IV: findings of stage III, but more advanced; narrowed cartilage space
• stage V: fibrous joint contractures, loss of the joint cartilage space, extensive enlargement of the epiphyses with substantial disorganization of the joint