Figure 3.

Cortical avulsive irregularity.

Coronal (A) and sagittal (B) T1-WI show a well delineated hypointense defect at the posteromedial femur above the level of the growth plate (arrow). On sagittal FS T2-WI (C), the lesion is of high signal but has a hypointense border (arrow). There is no associated soft tissue mass. Oblique plain film (D) shows cortical avulsive irregularity of the knee in another patient. The lesion is typically located at the posteromedial condyle of the femur, above the growth plate of the distal femur. The radiolucent defect is often surrounded by a rim of sclerosis (arrow).