Fig. 3
From: Surgical treatment of atlantoaxial subluxation by intraoperative skull traction and C1-C2 fixation
Radiographic parameters. a Atlas-dens interval (ADI): the distance between the posterior margins of the anterior arches of the C1 vertebra and the anterior margin of Odontoid process. b Atlantoaxial angle (A-A angle, the C1-C2 angle): the angle between the line connecting the lower margins of the anterior and posterior arches of the C1 vertebra and the lower margin of the C2 vertebra. c Atlantoaxial height (A-A height): the distance between the upper margin of the anterior arch of the C1 vertebra and the lower margin of the C2 vertebral body