Hoffa fat pad herniation

Last revised by Yuranga Weerakkody on 5 Sep 2019

Hoffa fat pad herniation is defined as herniation of infrapatellar fat through a defect in the lateral retinaculum. It is an uncommon cause of an anterolateral knee mass often detected at the fully flexed knee 1.

Clinical presentation

Mainly occurs in preschool-aged and young children as a painless soft mass along the anterolateral aspect of knee joint due to a focal defect in the lateral retinaculum.

In one of the recent MRI knee study, the focal defect in the lateral patellar retinaculum was found with 26% frequency. It was suggested as a normal variant rather than a pathologic change 2.

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Cases and figures

  • Case 1: on ultrasound
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