anterior humeral line

The anterior humeral line is key to demonstrating normal elbow alignment and should be used whenever reading a pediatric elbow radiograph to exclude a subtle supracondylar fracture.

Measurement

A line drawn down the anterior surface of the humerus should intersect the middle third of the capitellum.

Interpretation

When an axial force is applied down the radius (such as after a fall onto an outstretched hand), the radial head impacts the capitellum. This results in the narrowest and weakest part of the distal humerus is placed under stress. The result is often a fracture through the supracondylar portion of the distal humerus and this usually results in posterior displacement of the capitellum.

Where there is even minor displacement of the capitellum, look for evidence of an elbow effusion, or minor cortical irregularity on the AP and lateral film.

Unfortunately, as with all rules, there are exceptions. In most children, this rule holds for normal children. However, there are normal children (usually those under the age of 4) in whom the anterior humeral line passes through the anterior third. In these cases, look for ancillary signs to suggest elbow trauma.

Video tutorial 

See also

Anatomy: Upper limb

Anatomy: Upper limb