Pulled elbow

Pulled elbow is a traumatically induced medical affliction experienced only by children below the age of approximately three years.

The forearm contains two bones, the radius and the ulna. These bones are attached to each other both at the proximal, or elbow, end and also at the distal, or wrist end. Among other movements, the forearm is capable of pronation and supination, which is to say rotation about the long axis of the forearm. In this movement the ulna, which is connected to the humerus by a simple hinge-joint, remains stationary, while the radius rotates, carrying the wrist and hand with it. To allow this rotation, the proximal (elbow) end of the radius is held in proximity to the ulna by a ligament known as the annular ligament. This is a circular ligamentous structure within which the radius is free, with constraints existing elsewhere in the forearm, to rotate.The proximal end of the radius in young children is conical, with the wider end of the cone nearest the elbow. With the passage of time the shape of this bone changes, becoming more cylindrical but with the proximal end being widened.

If the forearm of a young child is pulled, by an impatient parent or for whatever reason, it is possible for this traction to pull the radius into the annular ligament with enough force to cause it to be jammed therein. This causes significant pain, partial limitation of flexion/extension of the elbow and total loss of pronation/supination in the affected arm. The situation cannot arise in adults, or in older children, because the changing shape of the radius associated with growth prevents it.

The condition can be treated by a primary care practitioner, and needs only minimal skill and total confidence. To resolve the problem, the affected arm must be held by the attending physician with one hand just above the elbow and the other grasping the hand. While applying compression between these two hands, the forearm of the patient is rapidly supinated. The physician will feel a "click", the child will scream, the parent (unless warned) will be upset, and the forearm will thereafter function well and painlessly.