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Case of the Week 344

What's the most likely diagnosis?

  • 12 year-old with pain in the knee after a fall

Left Knee-AP Radiograph

  1. Salter I fracture of tibia
  2. Fracture of the fibular head
  3. Osteosarcoma
  4. Benign cortical defect
  5. Dislocated patella

Additional Image - Left Knee-Lateral Image


Additional Image



Lateral image of knee




4. Benign Cortical Defect



More (Click Discussion Tab)

Benign Cortical Defect

General Considerations

  • Also called a non-ossifying fibroma or fibrous cortical defect
    • Non-ossifying fibroma frequently reserved for lesions > 2cm in size in older children
  • Usually arises in metaphysis of distal femur or tibia
  • Solitary lesion (75%) or multiple (25%)
  • Most commonly seen in children 2-15 years of age
  • May be secondary to a prior trauma injury (traction) as they tend to occur at sites of insertion of tendons and ligaments

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