The angle between the lines A–A and B–B normally opens laterally. If the angle opens medially, the patella is tilted. The line C is perpendicular to the line A–A and is drawn from the medial condyle. The line D is drawn 1 mm laterally from the line C and normally cuts the patella. If patella is located laterally from the line D it is said to be lateralized and has a dislocation tendency.