Object: The authors conducted a study to assess the correlation between radiological features and clinical courses in patients with chronic atlantoaxial rotatory fixation (AARF) and to determine diagnostic imaging signs for predicting prognosis.
Methods: There were 24 patients (eight boys and 16 girls) whose mean age was 7.8 years (range 4-14 years) and in whom AARF was diagnosed. The mean follow-up duration was 3.7 years (range 5 weeks-12 years). There were two groups of patients: 15 patients who visited the hospital less than 8 weeks after symptom (torticollis) onset comprised the acute group, and nine patients in whom the diagnosis of AARF was established later than 3 months after symptom onset comprised the chronic group. The chronic group was divided into two subgroups: those in whom the closed reduction could be achieved and those in whom it could not. Clinical data and radiographic studies, including plain radiographs and plain and three-dimensional (3D) computed tomography (CT) reconstructions, were reviewed retrospectively. A deformity of the superior C-2 facet joint was frequently observed in the group of patients with chronic AARF (p < 0.0001). This sign represented a risk factor for recurrent dislocation (p = 0.0003, Fisher exact test). Prominent lateral inclination of C-1 was an impeding factor for reduction of chronic AARF (p < 0.0001, analysis of variance with Fisher post hoc test). Greater than 20 degrees of lateral inclination of the atlas indicated an irreducible subluxation (p = 0.0023, Fisher exact test).
Conclusions: Both facet joint deformity and lateral inclination observed on 3D CT reconstructions can be useful signs to predict the prognosis and the treatment of choice in patients with chronic AARFs.