Presentation
Non-traumatic onset of the left hip pain for the last few months.
Patient Data
Gender: Male
From the case:
Crescent sign of femoral head avascular necrosis
Frog-leg view (magnified image)

There is a curvilinear subchondral lucency in the left femur head which a crescent sign of avascular necrosis of femoral head.
Case Discussion
The case shows a Crescent sign of femoral AVN. It suggest stage 3 of Ficat and Arlet classification of avascular necrosis of femoral head.