Snowcap Sign

A descriptive term for a broad radiopaque band which corresponds to diffuse homogeneous sclerosis and covers up to 23% of the femoral head’s articular surface in avascular and ischemic necrosis, caused by compromised epiphyseal blood supply, classically seen in posterior shoulder dislocation
DiffDx The sign is nonspecific and may occur in femoral head ischemia due to anaemia, haemophilia, endocrinopathy, congenital disease, or malignancy