Table 2 Measurement methods of the parameters
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 |