What anatomy is relevant to radial head subluxation?

Updated: Apr 08, 2020
  • Author: Gretchen S Lent, MD; Chief Editor: Erik D Schraga, MD  more...
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Answer

In maturity, the annular ligament encircles and supplies stability to the radial head (see the image below). In children, this ligament is not completely fused and thus is generally weak. Accordingly, when longitudinal axial traction is placed on a child’s extended pronated arm, the radial head may slip or tear through the weak annular ligament into the radiocapitellar articulation. [6] This results in entrapment of the annular ligament and subluxation (or partial dislocation) of the radial head.

Elbow anatomy with annular ligament. Elbow anatomy with annular ligament.

The left arm is more commonly involved, presumably because most caretakers are right-handed. Cases in which both elbows are subluxed at the same time have been reported. [7] Girls tend to be affected more often than boys are. Patients with prior radial head fractures are at risk for progressive radial head subluxation. [8]


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