1. The Floating Fat Sign of Trauma
Sayed Ali, MD, Stephen Huebner, MD, Frank Groshek, MD, Alyssa Schaffer, MD 
Canadian Association of Radiologists Journal 
Volume 65, Issue 2, Pages (May 2014)
DOI: /j.carj
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

2. Figure 1
Distal radius fracture with associated extensor tendon sheath fat. (A) An axial computed tomographic (CT) image of the distal radius, demonstrating a severely comminuted fracture (arrows) at the level of the extensor tendons. (B) An axial CT image in the soft-tissue window, showing fat within the tendon sheaths of the extensor carpi radialis brevis and extensor pollicis longus (arrows). (C, D) Sagittal reformatted CT images, demonstrating a spicule of bone (arrow in D) in intimate contract with the tendon sheath of the extensor pollicis longus, and distal tendon sheath fat (arrowheads in C) remote from the fracture.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

3. Figure 2
Synovial lipoma. An axial computed tomographic image, showing low-density fat within the semitendinosus tendon sheath (arrow).
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

4. Figure 3
Flexor hallucis longus tendon sheath fat. (A) Sagittal reformatted computed tomographic (CT) image, demonstrating a comminuted intra-articular fracture of the calcaneus (arrows) with extension into the subtalar joint. (B) An axial CT image, showing fat density (arrow) within the flexor hallucis longus tendon above the level of the ankle joint, remote from the fracture. (C) Coronal and (D) sagittal reformatted images at soft-tissue windows, showing distal fat in the flexor hallucis longus tendon sheath at the distal master knot of Henry (arrow in C and D), distinctly remote from the fracture site.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

5. Figure 4
Biceps tendon sheath fat. (A) Axial computed tomographic images, showing fat in the proximal biceps tendon sheath. (B) A sagittal reformatted image, showing fat migrating proximal to the fracture site.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

6. Figure 5
(A) Fat in the posterior tibial tendon (PTT) sheath (arrow). (B) Proximal migration of fat in the PTT sheath to the level of the medial malleolus (arrow). (C) Navicular fracture seen on thin-section computed tomography (arrow).
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

7. Figure 6
(A) A normal radiograph. (B) Fat in the peroneus longus tendon sheath (arrows). (C) Fracture of the first metatarsal base is seen on computed tomography (arrow).
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

8. Figure 7
Morel-Lavallee lesions. (A) Lateral radiograph, demonstrating a nondisplaced fracture of the medial femoral condyle posteriorly (Hoffa fracture [arrow]) with fat-fluid level in the prepatellar soft tissues (arrowhead). (B) An axial T2-weighted magnetic resonance image in the same patient, demonstrating multiple fat-fluid levels consistent with Morel-Lavallee lesions in the soft tissues of the medial knee (arrows) and the posterior medial femoral condyle (Hoffa) fracture (arrowhead). The anterior lesion on the magnetic resonance image corresponds to the radiographic finding.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

9. Figure 8
Subperiosteal floating fat. Sagittal reformatted (A) and axial (B) computed tomographic images of the ankle, demonstrating a highly comminuted intra-articular fracture of the distal tibia (arrows in A), with an extensive fat-fluid level seen in a subperiosteal location anterior to the tibia, constrained by the periosteum (arrowheads in A and B). Note the distance of the fat-fluid level from the fracture.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

10. Figure 9
Lipohemarthrosis. (A) Sagittal reformatted computed tomographiy (CT) of the calcaneus, showing a calcaneal fracture. (B) An axial CT image in soft-tissue windows, showing a large lipohemarthrosis (arrowhead), which confirms that the fracture is intra-articular. There is also possible fat in the flexor hallucis longus tendon sheath; however, this was the last image on the series (arrow).
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

11. Figure 10
Hoffa fat pad fracture. Sagittal fat-suppressed fast spin-echo T2-weighted image, showing a fracture of the Hoffa fat pad (arrow) in a patient with high-velocity trauma. Free-floating fat was not demonstrated in this case.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions

12. Figure 11
Intra-articular lipoma. Sagittal (A) and coronal (B) reformatted computed tomographic images at soft-tissue windows, showing a large intra-articular knee lipoma (arrow). The absence of a fat-fluid level differentiates this from a lipohemarthrosis, but, if an effusion were present, then the distinction could be more difficult.
Canadian Association of Radiologists Journal  , DOI: ( /j.carj )
Copyright © 2014 Canadian Association of Radiologists Terms and Conditions