Imaging of traumatic injury and impingement of anterior knee fat.
Fat is not just used by the body as bulk tissue. In addition to its role in storing energy and regulating hormone action, fat is used in some parts of the body for its mechanical properties. The anatomy of anterior knee fat is more complex than it appears at first sight and is capable of withstanding considerable compressive and shear stress. Specific lesions occur when such mechanical stress exceeds the physiological limits and are yet little known. Superficial fat can be the site of either acute injury by closed degloving called the Morel-Lavallée lesion or chronic injury, when subject to repeat excessive shear forces, due to more complex and less well-defined disruptions that result in pseudo-bursitis. There are three main anterior, intracapsular and extrasynovial fat pads in the knee joint, which are the infrapatellar fat pad (IFP) or Hoffa's fat pad, the quadriceps fat pad and the prefemoral fat pad. The IFP plays an important role as a mechanical shock absorber and guides the patella tendon and even the patella itself during flexion-extension movements. In response to repeated excessive stress, an inflammatory reaction and swelling of the IFP is first observed, followed by a fibrotic reaction with metaplastic transformation into fibrous, cartilaginous or bone tissue. More rarely, the two other deep fat pads (quadriceps and prefemoral) can, if subject to repeated stress, undergo similar restructuring inflammatory reactions with metaplasia resulting in tissue hardening, anterior pain and partial loss of function.
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France; Centres d'imagerie du Languedoc, 26, rue Ernest-Cognacq, ZAC Bonne source, 11100 Narbonne, France. Electronic address: franck.lapegue@gmail.com.
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Lapègue
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Sans
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Brun
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Bakouche
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Brucher
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Cambon
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Chiavassa
Service d'imagerie médicale, CHU de Nîmes, place du Pr-R.-Debré, 30029 Nîmes cedex 9, France.
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Larbi
Service d'imagerie, CHU de Toulouse-Purpan, bâtiment Pierre-Paul-Riquet, place du Dr-Baylac, TSA 40031, 31059 Toulouse cedex 9, France.
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Faruch
D000273:Adipose Tissue / Q000000981:diagnostic imaging* / Q000293:injuries*; D002062:Bursitis / Q000000981:diagnostic imaging; D017276:Friction / Q000502:physiology; D006801:Humans; D007718:Knee Injuries / Q000000981:diagnostic imaging*; D007719:Knee Joint / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D017847:Patellar Ligament / Q000000981:diagnostic imaging / Q000503:physiopathology; D013180:Sprains and Strains / Q000000981:diagnostic imaging; D050151:Subcutaneous Fat / Q000000981:diagnostic imaging* / Q000293:injuries*; D013585:Synovitis / Q000000981:diagnostic imaging
Bursitis; Fat pad; Hoffa's syndrome; Knee; Morel-Lavallée lesion