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Table 2 Measurement methods of the parameters

From: Association of patellofemoral morphology and alignment with the radiographic severity of patellofemoral osteoarthritis

Parameters Definition
PFJ morphology
 Sulcus angle SA This angle is defined by lines joining the highest points of the medial and lateral condyles and the lowest point of the intercondylar sulcus
 Lateral trochlear inclination LTI The angle between the lateral facet line of trochlea and posterior condylar line
 Medial trochlear inclination MTI The angle between the medial facet line of trochlea and posterior condylar line
 Wiberg classification Wiberg Type I, the facets are symmetrical, concave, and of equal size
Type II, the medial facet is smaller and flatter compared to the lateral facet
Type III, the medial facet is convex, more vertical, and markedly smaller
PFJ alignment
 Congruence angle CA The line through the apex of the patella to a line bisecting the trochlea
 Patella tilt PT The angle between the posterior condylar line and the maximal patella width line
 Lateral patellar angle LPA The angle between the lateral facet line of patella and the line joining the highest points of the medial and lateral condyles
 Caton-Deschamps index CDI The ratio between the length of the distance from the lower edge of the patellar articular surface to the anterior superior surface of the tibial plateau and the length of the patellar articular surface
 Tibial tubercle–trochlear groove distance TT-TG The TT-TG distance is the distance from the deepest point of the trochlear groove to the highest point of the tibial tuberosity
  1. PFJ patellofemoral joint