Fig. 1

Ten measures of patellar alignment clockwise from top left: a bisect offset (BO); b trochlear inclination (TI); c sulcus angle (SA); d patellar lateral subluxation distance (PSD); e lateral patellofemoral angle (LPFA); f lateral patellar displacement distance (PSD); g trochlear angle (TA); h congruence angle (CA); i patellar tilt angle (PTA); j patellar length ratio (PLR). For congruence angle, the angle AB is bisected by O, and the congruence angle is the angle from the lowest point of the inferior margin of the patella to the line O. Note that trochlear angle is split into medial and lateral components, giving a total of eleven measurements for each patient