Reliability and head-loading effects in imaging diagnosis of vertical subluxation in patients with rheumatoid arthritis.

OBJECTIVES: The purpose of this study was to examine the reproducibility of vertical subluxation (VS) parameters using X-ray, computed tomography (CT), and tomosynthesis (TS) while comparing the head-loading effects. METHODS: The VS parameters of 26 patients (retrospective review) were evaluated. Using the intra-class correlation coefficient, we statistically examined the intra-rater and inter-rater reliabilities of the parameters. Head-loaded and -unloaded imagings were compared using a Wilcoxon signed-rank test. RESULTS: The intra-rater reliability of TS and CT showed intra-class correlation coefficients of ≥0.8 (X-ray range: 0.6-0.8), with similar results for the inter-rater reliabilities. Furthermore, in head-loading imaging, the TS had significantly higher VS scores than that of CT (P < .05). CONCLUSIONS: In comparison with the X-ray, TS and CT were more accurate and reproducible. In terms of head loading, the VS values for TS were worse than those for CT, indicating that TS was more effective than CT in diagnosing VS.