The reduction of a supracondylar fracture of the humerus can become a comparatively simple feat if it is undertaken without delay and if the surgeon who has the first opportunity of treating it has a clear mental picture of its mechanism. The first reduction is the one most likely to succeed; after subsequent attempts the elbow becomes so indurated that the swelling may obstruct even the most expert manipulator.

ANATOMY OF THE FRACTURE

In the supracondylar fracture of the humerus the fracture line passes more or less transversely through the metaphysis at a variable distance from the epiphyseal line. When the fracture line is extremely close to the epiphyseal line it sometimes appears in the X-ray almost as an epiphyseal separation, but in every case a thin shell of the diaphysis is adherent to the distal fragment.

There are three elements in the displacement of the distal fragment of the supracondylar fracture: (i) posterior displacement, (2) lateral (or medial) displacement, and (3) rotary displacement.

In the manipulative reduction to be described, the rotary deformity will more or less correct itself under the influence of the tense fascial structures in the course of the preliminary phase of reduction by traction. An error of 10 degrees of rotation will not affect the functional or cosmetic result, though it will give rise to interesting appearances in the radiograph which need special comment (see below).