Lateral patellar subluxation is seen, with medial patellofemoral ligament tear. Moderate knee joint effusion is seen with associated patella alta. The demonstrated images show (in order):
Sagittal T2 shows patellar height ratio normal value should be 1. Patella alta seen in this case.
Axial STIR shows trochlear facet asymmetry calculated as 10/24 x 100 = 41%Normal value is 60-70%. Less than 40 degree is trochlear dysplasia. This case is borderline trochlear dysplasia.
Axial STIR shows lateral trochlear inclination. Normal value 20-25 degree & lt 11 degree is considered trochlear dysplasia.
Axial T1 shows lateral patellofemoral angle. Angle opening laterally is considered normal. In this case, it is opening medially.
Axial T2 shows 'Q' angle & lt;15 mm is normal,15-20 mm is borderline. Distance of more than 20 mm is significant, as seen in this case, and suggests medial patellofemoral subluxation.
Axial STIR shows trochlear depth. It is calculated as (55.6+50.9/2) - 48.9 = 4.0 mm. Normal depth is 12 mm. Less than 3 mm is considered dysplasia. This case shows borderline trochlear dysplasia.