OSTEOCHONDRITIS DISSECANS

Sub-articular, post-traumatic necrosis

Occurs only on convex surfaces of bone

• Medial condyle of femur

• Capitellum
• Proximal surface of talus
• Head of 1st metatarsal

Most patients are athletic

Direct blow is more common cause than a rotational injury

• Knee lesions are more common amongst high jumpers

Most common cause of an intra-articular loose body

In adults, loose body contains larger fragment of cartilage than bone

Possible outcomes

• Death of bony, but not cartilaginous, portion of loose body

• Loose body is invisible except to MRI
• Complete resorption of loose body
• Reincorporation or regrowth
• Usually not in adults
• In children, fragment is less likely to separate from bone and therefore more likely to reincorporate

Cause of a “locking knee”

 

 

Osteochondritis dissecans. Blue arrow points to crescentric lucency in the convex
surface of the medial condyle of the knee.

For the same photo without the arrows, click here.

Osteochondritis dissecans. Red arrows point to osteochondral defect and bone edema on T1 and stir
MRI images of the knee in same patient as above. .

 

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