Which imaging findings of the knee are characteristic of hemophilia?

Updated: Sep 27, 2019
  • Author: Lars J Grimm, MD, MHS; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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The knee is the classic target joint. Involvement of this joint is most commonly described in the literature and is the basis for the findings described in the Arnold-Hilgartner classification (see the table below). [5]

The chronic joint effusions in hemophilia may be denser than other effusions because of the presence of iron. Juxta-articular osteoporosis develops, especially in children, secondary to the hyperemic state. The irregular appearance of the subchondral surface is secondary to either blood that directly destroys bone or to synovial intrusion.

Deeper invasion of the synovium and joint fluid leads to multiple subchondral cysts. Chronic hyperemia causes overgrowth of the epiphysis and widening of the intercondylar notch in the growing child. Squaring of the inferior pole of the patella (seen in 20-30% of patients with hemophilia) is another form of overgrowth. A similar effect of overgrowth may be seen in children with juvenile rheumatoid arthritis (JRA).

Table. Arnold-Hilgartner classification [19] (Open Table in a new window)




Normal joint


No skeletal abnormalities, soft-tissue swelling is present


Osteoporosis and overgrowth of the epiphysis, no cysts, no narrowing of the cartilage space


Early subchondral bone cysts, squaring of the patella, widened notch of the distal femur or humerus, preservation of the cartilage space


Findings of stage III, but more advanced; narrowed cartilage space


Fibrous joint contracture, loss of the joint cartilage space, extensive enlargement of the epiphysis, substantial disorganization of the joint

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