Fielding classification of atlanto-axial rotatory fixation

In 1977, Fielding and Hawkings divided atlantoaxial roratory subluxation into the following four types.

Type Description Ligaments
Type I Simple rotatory displacement (rotatory fixation) without anterior shift. The transverse ligament is intact and the dens acts as pivot
Type II Rotatory fixation with anterior diplacement between 3 and 5mm. The transverse ligament is injured and the opposite facet acts as pivot.
Type III Rotatory fixation and anterior displacement >5mm. The transverse ligament and facet capsules are injured. Both lateral atlantoaxial joints are subluxed anteriorly.
Type IV Rotatory fixation and posterior displacement. Both lateral atlantoaxial joints are subluxed posteriorly.

Anterior displacement >4mm in small children and >3mm in adults is abnormal.


1. Fielding JW, Hawkins RJ. Atlanto-axial rotatory fixation. (Fixed rotatory subluxation of the atlanto-axial joint). J Bone Joint Surg Am. 1977 Jan;59(1):37–44.