• Small: 160 degrees or less
  • Medium: 161 – 199 degrees
  • Large: 200 or more degrees


The Kerboul angle, also known as the “combined necrotic angle,” is a system used to quantify the size of a lesion. To calculate, first identify the center of the femoral head. Two lines are then drawn from this point to the borders of the lesion on both AP and lateral radiographs. The sum of the angles on the AP and lateral radiographs is the Kerboul angle. Lesions are classified as small, medium, or large.



Provide the citation for the landmark article and recent review articles describing the classification