Axial PD-weighted TSE MRI of a 15-year-old male with a recurrent LPD. At the medial facet of the patella, a full-thickness defect of the cartilage (grade 4) with ulceration of the bone is demonstrated (white arrows). At the lateral femoral condyle, a cartilage composing > 50% of the cartilage thickness and showing a small ulceration to the subchondral bone is defined as a grade 3 lesion (black arrow).