Open mouth (odontoid) view of C1/C2 dislocation

The AP open mouth view of C1/C2 intervertebral joint space and the odontoid reveals an obvious offset of the right lateral mass of C1 (arrow) over the corresponding lateral mass of C2. There is more subtle malalignment of left C1 lateral mass (arrowhead) relative to C2. These findings suggest a Jefferson fracture of C1.