Dynamic Mri exam is crucial in many situations; in a previous post I have shown a dynamic Mri study of patellofemoral impingement with patella alta.
Take a look at this patient in which the suspected patella baja is well studied during flexion-extension active movements.
Rember that in case of true patella baja, the patella remains engaged within the trochlear groove in full knee extension. The dynamic examination allows to appreciate the direct visualization of patellar and trochlear allignment for a more objective measurement, together with the others modalities. In this patient the dynamic examination shows a correct patellar positioning during active extension.