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.
References:
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.
Updated 9/8/2013 11:23 by Lambert