Teaching Case

Pain of the right distal forearm after a fall.

The patient complained of swelling and distal forearm pain after a fall on his right outstreched wrist and hand. Routine X-ray films revealed the typical appearance of torus fracture of radius and ulna (figure 1).

Longitudinal compression of the bone can cause incomplete fractures in children because of the unique relative plasticity of their bones. These include bowing, torus, greenstick and stress factures. Torus is derived from latin (tori), meaning a swelling or protuberance. Also known as a buckle fracture, this is an impaction fracture in which the cortex around all or part of the circumference of the bone is buckled. Although it can occur in any long bone, the distal radius is the most common site (1). This type of fracture usually occurs near the metaphysis, where the porosity of the bone is greatest, and is most common in children (2). The etiology is usually a fall on an outstretched arm. The child usually presents with a painful and swollen wrist. Radiographic finding is a definite cortical bulge usually occurring at the metaphysis, two to four centimeters from the distal growth plate (figure 1). This sign is often better seen on the lateral film (figure 2). It is wise to include both the wrist and elbow to rule out dislocation of the proximal and distal radio-ulnar joints. Occasionally, the radiograph is normal and the diagnosis must be made from the clinical findings.
A combination of a greenstick and torus fractures is termed lead pipe fracture (figure 3) (4).