Fig. 1
From: Patellar instability: the reliability of magnetic resonance imaging measurement parameters
Measurements of patellar position: a the angle of Fulkerson is the angle between C and A; b the angle of Grelsamer is the angle between D and the horizontal axis; c the angle of Laurin is the angle between C and B; d patellar tilt angle (PTA) is the angle between D and A; e lateral patellar displacement (LPD) is the shortest distance between E and F; f bisect offset ratio (BSO) = L/P; and (g) congruence angle (CA) is the angle between G and H