DIAGNOSIS:-

Note the curvature of the ulna which is excessive. This represents a "bowing fracture" of the ulna. Bowing fractures usually occur in the forearm. This is a bending deformity without a grossly visible fracture in the tubular structure of the bone. Microfractures are present on microscopy, but only the bowing is appreciable on plain radiographs. Reduction of a bowing fracture requires a lot of force, thus it should be done under general anesthesia. Failure to recognize a bowing fracture of the forearm results in limited supination and pronation. Periosteal reaction on later radiographs may not occur with bowing fractures so this cannot be used as a criterion to rule out an earlier fracture. A comparison view of the other extremity may be useful in identifying the bowing fracture.

View comparison of the other forearm

This comparison view shows the normal configuration of the unaffected right radius and ulna on the right image. Comparing this with her affected left forearm (left image), it is easier to appreciate the bowing deformity of the ulna. However, note that the two are not very different since the bowing of the left ulna is not severe.

Arrows point to the bowing deformity of the ulna.

Examine the left forearm in isolation.
See if you can appreciate the bowing deformity of the ulna.

In this case, the clinical appearance of a deformed forearm is highly indicative of a fracture. If radiographs fail to confirm the presence of an obvious fracture, consider the possibility of a bowing fracture.

References:

1. Diaphysis (Chapter 16). In: Harris JH, Harris WH, Novelline RA. The Radiology of Emergency Medicine, third edition. 1993, Baltimore, MD, Williams & Wilkins, pp. 1059-1061.
   

Copyrighted:Radiology Cases in Pediatric Emergency Medicine Volume 1, Case 1 Loren Yamamoto, MD, MPH, Professor of Pediatrics, University of Hawaii John A. Burns School of Medicine.Loreny@hawaii.edu

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Last created on 01-07-2006