A difficult delivery of a newborn infant may result in a traumatic
separation of the proximal humeral epiphysis from the metaphysis through
the physis. When the ossification center of the epiphysis is not yet
visible radiographically, the correct diagnosis may be missed and the
injury may be mistaken for a dislocation or Erb palsy. As a non-invasive
diagnostic method, ultrasonography has proved to be a particularly valuable
diagnostic tool.