The first thing the reporting radiographer should look for on a radiograph of a traumatized elbow (apart from the name and marker) is the distal humeral fat pads on the lateral view. On a normal elbow the anterior fat pad should lie flat against the humerus and the posterior one is usually not visible, as it lies in the olecranon fossa, see image 1. Elevation of one or both fat pads usually indicates the presence of underlying trauma. This is not a hard and fast rule as the author can say he has seen both fat pads elevated and no evidence of bony trauma, even after follow up radiographs, and he has seen obvious bony trauma with no elevation of the fat pads. It is however normally true and gives a good indication of what to look for. In image 2 the reader can see that both anterior and posterior fat pads are elevated, sometimes called the sailboat sign (the image is enhanced to improve the clarity of the fat pads, this is of course not a diagnostic image). A fracture of the radial head usually elevates the anterior fat pad only, whereas a supracondylar fracture of the humerus will almost certainly elevate both fat pads.

In Brighton it is not common practice to produce extra views to find a bony injury, the elevation of one or both fat pads is evidence enough of trauma and the patient will be treated clinically even if no bony trauma is seen.

THE DISLOCATED ELBOW.

There should be no difficulty in seeing a dislocation of the elbow, they are usually one of the most dramatic looking injuries, see images 3 and 4. There is however one associated injury the reporting radiographer should be careful not to miss. Occurring in older children and adolescents, it is the avulsion of the medial epicondylar apophysis. Images 5 and 6 show the initial injury with the apophysis lying in the humero-ulna joint space. It is a little difficult to see the avulsed medial epicondyle on the A.P. view, but it is conveniently bisected by a linear artifact from a positioning pad. Image 7 shows the repair.

Avulsion of the medial epicondyle apophysis can occur without a dislocation, see image 8. It can be seen that there is an abnormally wide gap between the humerus and the apophysis. Also there is a small bony fragment lying in the gap. This is a small fragment from the diaphysis.

Image 9 shows the appearance of an un-united avulsion persisting into adulthood. An un-united apophysis can also occur as a normal variant as in image 10 but the apophysis normally lies closer to the humerus.

THE FRACTURED HEAD OF RADIUS.

The radial head fracture is often difficult to see or unseen (occult). The sign to look for as previously mentioned is the elevation of the anterior humeral fat pad. Images 11,12 and 13 show examples of radial head fractures.

Image 14 shows a fracture across the neck of the radius which was not so obvious on the A.P. view, image 15.

NORMAL VARIANTS.

Image 16 shows a cleft epiphysis of the radial head. This resembles a fracture, but close inspection of the original radiograph would show that the edges are even and corticated.

Image 17 shows a quite large antecubital ossicle.