Fig. 1

PD MR images of a 34-year-old healthy male subject. a Line 1 was drawn through the deepest cartilaginous point of the trochlear groove to form a 90° angle with the posterior condylar line. b Line 2 was drawn in parallel to line 1 from the center of the patellar tendon (closest to the tibial tubercle) extending to the original posterior condylar line. The distance between lines 1 and 2 represents the TT-TG