72.6 Supracondylar fracture of the humerus in children with anterior displacement of the distal fragment

Anterior displacement of the distal fragment of a supracondylar fracture is rare, and the signs are milder than with posterior displacement. Make the diagnosis from the lateral Xray, as shown in B, Fig. 72-7. This may be difficult to interpret because the lower end of the diaphysis overlaps the epiphysis, especially in a young child, so that the epiphysis may appear to be displaced when it is not. The best test is to look at a lateral X–ray and to see where a line drawn down the front of the humerus cuts the curved lower border of the epiphysis, this is the line A–B in Fig. 72-3. It should bisect it as in Fig. 72-3. The epiphysis should not lie in front of this line.

A CHILD’S SUPRACONDYLAR FRACTURE ANTERIORLY DISPLACED

Anaesthetize the child as for forward displacement (72.8). Extend his forearm. Ask an assistant to exert steady traction in the line of his arm with his forearm supinated.

While your assistant is doing this, steady the lower end of his humerus with one hand, and correct the sideways displacement of the lower fragment with your other hand.

Either, put his arm up in traction as in Fig. 72-11, or apply a 10 cm plaster slab along the back of his arm and forearm with his elbow extended. Keep it in place with a crepe bandage.

Confirm reduction with an X–ray. Remove the slab in 3 weeks in a child and put his arm in a sling.

Alternatively, flex his elbow to 90, and push his forearm posteriorly on his upper arm so as to convert the anterior displacement to a posterior one. Then, treat it as you would a posterior displacement (72.6 ).