Fig. 3A–C.

(A) On the slice where the posterior femoral condyles were largest, a line was drawn on their posterior surface (posterior condylar line). Then a line perpendicular to this line was projected anteriorly through the center of the femoral trochlea. (B) The patella tilt angle is the angle between the posterior condylar line and the maximal patella width line. (C) Bisect offset is equal to the length of the patella lateral to midline/maximal patella width × 100. (Published with permission and adapted from from Stefanik JJ, Zhu Y, Zumwalt AC, Gross KD, Clancy M, Lynch JA, Frey Law LA, Lewis CE, Roemer FW, Powers CM, Guermazi A, Felson DT. Association between patella alta and the prevalence and worsening of structural features of patellofemoral joint osteoarthritis: the multicenter osteoarthritis study. Arthritis Care Res. 2010; 62: 1258–1265. Copyright (2010) Wiley.)