Elbow sprain from the monkey bars?

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An 8 year old female presents to the ED after falling off the monkey bars at school, complaining of pain in her elbow.

Exam Findings

There is tenderness over the lateral aspect of the elbow and reduced range of motion on flexion, supination, and pronation due to pain.

Distally, the exam is negative. Possibly, there is some very mild elbow swelling, but this is not obvious.

There are no deformities. Sensation is intact distally. The radial pulse is present at the wrist.

The proximal humerus, shoulder, and clavicles are non-tender.

Investigations

Radiographs of the elbow are obtained.

Elbow X-rays

View elbow XR comments

These radiographs show a very subtle fracture of the radial head at the metaphysis. This can be seen as a slight interruption in the smooth contour of the metaphysis. The anterior fat pad is prominent.

The radial head fracture is best seen on the AP view on the lateral size (left on the screen) of the radial metaphysis as a slight irregularity in the cortex.

An additional oblique view shows the fracture somewhat better.

 

Discussion & Teaching Points

  • A radial head fracture is not always easy to appreciate. The patient’s symptoms may be relatively mild. Flexion and extension of the elbow are frequently unremarkable. Supination and pronation may be more limited and/or painful. There is often tenderness over the radial head. Since radial head fractures tend to occur in older individuals, it is unlikely to be mistaken for a subluxed radial head as in a nursemaid’s elbow; however, since it can occur in younger children also, this diagnosis should still be considered if the history does not suggest a classic pulling injury.
  • A sprain injury of the elbow is a diagnostic pitfall that should be avoided. This patient does NOT have an elbow sprain. Occult fractures in the elbow are often present and difficult to appreciate radiographically. A normal set of radiographs, even after review by radiologists, are not able to totally rule out a fracture. It may be useful to routinely issue a standardised instruction sheet explaining this possibility to patients.
  • Elbow injuries are fracture prone. Radiographs of this area can be difficult to interpret unless a methodical review of the radiographs is performed. One of the things that should be carefully inspected is the contour of the radial head. The slope from the diaphysis to the metaphysis towards the radial head should be gradual and smooth with no sharp angles associated with it. It should NOT look like the end of a baseball bat (handle end).

View radiograph in a teenager

 

Teenager

 

This radiograph shows a subtle fracture of the radial head. Note the very slight corner interrupting the smooth contour of the radial head metaphysis. The radial head appears to resemble a knob on a pole rather than a funnel shape.

The smooth contour of the radial head as one proceeds from the epiphysis to the metaphysis should be carefully inspected. Any angles noted in this smooth progression may represent a fracture, especially if the clinical findings confirm this.

View radiograph in a toddler

 

Toddler

 

This radiograph shows a fracture of the radial head. Note the sharp angle seen at the radial head metaphysis. This patient presented with symptoms similar to a nursemaid’s elbow; however, the history did not suggest a pulling injury.

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About 

Prof Loren Yamamoto MD MPH MBA. Professor of pediatrics at the University of Hawaii and a practising pediatric emergency doctor in Honolulu. | Contact | View Loren's DFTB posts