Extra-capsular floating fat at the extremity: a review

Extra-capsular floating fat may present in a variety of non-articular locations at the extremity. Manifestation of floating fat or fat-fluid level(s) outside of a joint is a marker of trauma or infection. Recognizing radiologic sign(s) of extra-capsular floating fat can aid radiologists to provide an informed differential diagnosis and facilitate clinical care. This review discusses the etiology, mechanisms, and imaging appearance of extracapsular floating fat in specific anatomic and non-anatomic locations at the extremity.