Figure 3b:

Sagittal intermediate-weighted fat-saturated two-dimensional fast spin-echo MR images of the right knee in two subjects with signal abnormalities at baseline and with focal defects after 48 months. (a) Hyperintense signal abnormality in the trochlea at baseline (arrows). (b) Development of a focal partial thickness defect in the same location as in a (white arrow) (WORMS grade 2) at 48 months. Note the adjacent hypointense area in the cartilage (black arrow), indicating further cartilage degeneration. (c) Hypointense signal abnormality of the patella at baseline (arrow). (d) Development of a fissure (arrow) (WORMS grade 2) in the same patient as in c at 48 months.