Fishtail deformity of elbow

Case contributed by Andrew Dixon
Diagnosis certain


Fall onto left elbow.

Patient Data

Age: 4
Gender: Female

Supracondylar humerus fracture with associated hemarthrosis. 

8 months later


Radiographs 8 months later reveal healing of the supracondylar fracture but development of new lucency and collapse at the metaphysis adjacent to where the trochlear ossification center is due to develop. This post-traumatic phenomenon is known as a fishtail deformity. 

Annotated image

Lucency and collapse at the metaphysis on the trochlear side of the distal humerus (green arrow) creating a fishtail indentation. 

Case Discussion

Fishtail deformity of the elbow is characterized by a contour abnormality of the distal humerus, which develops when the lateral trochlear ossification center fails to develop or resorbs. It is an uncommon complication usually following a distal humeral fracture in childhood.

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