Fig. 4.

Superolateral infrapatellar fat pad (Hoffa fat pad) impingement in a 46-year-old woman with lateral infrapatellar knee pain. (A) Sagittal and (B) axial fat-suppressed proton-density MR images reveal high signal intensity (edema) in the superolateral aspect of Hoffa fat pad between the lateral aspect of the patellar tendon and the lateral femoral condyle (solid arrow). Additionally there is focal thickening and increased signal in the lateral aspect of the patellar tendon consistent with tendinosis (arrowhead). Note high riding patella with a modified Insall-Salvati: distance between distal patellar articular surface and distal patellar tendon insertion (dashed double end arrow)/patellar length (solid double end arrow) is 2.4 (greater than 2). No trochlear dysplasia or lateral patellar displacement was found in this case.