The Positive fat-pad sign: what is it?
Radiology
Written by Dr. Terry R. Yochum, D.C.; D.A.C.B.R.; Fellow, A.C.C.R. and Dr. Chad J. Maola, D.C.   
Friday, 30 May 2003 00:00 Read : 3549 times

A useful sign of an intraarticular fracture of the elbow is the clear depiction of displaced humeral capsular fat-pads.1  In the normal elbow, a layer of fat (“fat-pad”) lies between the synovial and fibrous layers of both the anterior and posterior joint capsules.  In the lateral projection of the normal elbow, the anterior fat-pad is seen as an obliquely oriented radiolucency.  When acute intracapsular swelling is present from any origin (hemorrhagic, inflammatory, or traumatic), the anterior fat-pad is elevated to be oriented horizontally, while the posterior fat-pad, when visible, is the most reliable sign of intraarticular effusion.  In children and adolescents, 90% of posterior fat-pad signs will have an associated fracture.1  In adults the sign is less frequently seen, and its absence does not exclude the presence of a fracture.2, 3 

 

 

 

 

Figure 1. Observe the displacement of the posterior fat-pad from the olecranon fossa (arrow). This usually indicates a hidden fracture Figure 1
Figure 2 Figure 3

 

Figure 2 and Figure 3. There is an impaction fracture of the radius (arrow). This patient fell on outsreched hand, locked her elbow and had a positive fat-pad sign.


 

References

  1. Norell G:  Roentgenologic visualization of the extracapsular fat.  Its importance in the diagnosis of traumatic injuries to the elbow.   Acta Radiol 42:205, 1954.
  2. Hunter RD:  Swollen elbow following trauma.  JAMA 230:1573, 1974.
  3. Yochum TR, Rowe LJ:  Essentials of Skeletal Radiology, 2nd ed., Williams & Wilkins, Baltimore, Maryland, 1996.


Dr. Terry R. Yochum is a second-generation chiropractor and a cum laude graduate of the National College of Chiropractic, where he subsequently completed his radiology specialty.  He is currently Director of the Rocky Mountain Chiropractic Radiological Center, in Denver, CO, an Adjunct Professor of Radiology at the Los Angeles College of Chiropractic, as well as an instructor of Skeletal Radiology at the University of Colorado School of Medicine, Denver, CO.  Dr. Yochum is, also, a consultant to Health Care Manufacturing Company that offers a Stored Energy system.  For more information, Dr. Yochum can be reached  at: (303) 940-9400 or by e-mail at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Dr. Chad Maola is a 1999 Magna Cum Laude Graduate from National College of Chiropractic.


 
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