The cervical spine x-rays were initially read as normal by the radiologist.
CT scan images showed that the cervical spine was not normal.
In retrospect, the lateral view of the cervical spine shows that the “ring” of C2 has been disrupted and that there is some soft tissue swelling anterior to the vertebrae. The AP view shows a fracture through the base of the odontoid, classifying this as a “Type II” fracture.
Recall that there are three Anderson/D’Alonzo classifications of odontiod fractures, with the numbers getting larger as the site of the fracture gets lower:
Type I: Through the tip of the dens
Type II: Through the base of the dens
Type III: Through the body of C2
All are treated with a halo vest.