Cortical Desmoid

Lateral view of the knee radiograph shows focal cortical irregularity and thickening at the posterior aspect of the medial condyle of the femur (arrow), consistent with a cortical desmoid. The arrowhead points to a fabella.

Facts: Cortical Desmoid

• Considered to be an avulsion of the medial supracondylar ridge of the distal femur
• Occurs only on the posteromedial epicondyle of the femur (insertion of adductor magnus aponeurosis)
• Common in older children
• Patients may complain of pain, or being asymptomatic (incidentally detected on radiograph done for other reasons)
• They may or may not show periosteal reaction; 1-3 cm in size, mixed sclerosis and lucency in the cortex

Reference:

Helms CA. Fundamentals of skeletal radiology, 3rd edition, 2005.