Dynamic close-mouth view radiograph method for the diagnosis of lateral dynamic instability of the atlantoaxial joint.

The purpose of the current study is to establish the dynamic close-mouth view radiograph method. Seven healthy volunteers were enrolled. Dynamic open-mouth and close-mouth view radiographs were obtained. The odontoid lateral mass interval and the dynamic atlantodental lateral shift (ADLS) were measured. The ADLS was 9.4+/-5.3% by the close-mouth view, showing a significantly greater percentage than that of 5.3+/-4.0% by the open-mouth view. The dynamic close-mouth view can be useful for diagnosis of atlantoaxial lateral instability.