Introduction: Atlanto-axial rotatory fixation is a rare condition which occurs more. commonly in children than in adults. The terminology can be confusing and the condition is also known as. ‘ atlanto-axial rotatory sub-luxation’ and ‘atlanto-axial rotary dislocation’ . Rotatory fixation is the preferred term however , as in most cases the fixation occurs within the normal range of rotation of the joint and by definition therefore the joint is neither subluxed nor dislocated. Atlanto-axial rotatory fixation is a cause of acquired torticollis. Diagnosis can be difficult and is often delayed. The classification. system proposed by Fielding in 1977 is most frequently used and will be discussed in detail. Given that this classification system was devised in the days before CT, as well as the fact that combined atlanto-axial and atlanto-occipital rotatory subluxation is omitted from the classification, we propose a modification to the classification of this rare but significant disorder.

Methods and Results: The radiological findings in six cases of atlanto-axial rotatory fixation will be illustrated, including a case with associated atlanto-occipital sub-luxation. The pertinent literature will be reviewed and a more comprehensive classification system proposed. The imaging approach to diagnosis and the orthopaedic approach to management will be discussed.

Conclusion: In general, children who present with a traumatic torticollis should be treated conservatively with cervical collar and anti-inflammatory medication for one week. Those children whose torticollis fails to resolve after one week require aggressive investigation by ‘dynamic’ computed tomography to assess whether the joint is fixed. If however there is a history of significant trauma then immediate radiological assessment is advised. This approach will avoid over-investigation and over-treatment yet will still detect atlanto-axial rotatory fixation early enough to achieve a good outcome.