Thoracic spine disc degeneration, translation, and angular motion: An analysis using thoracic spine kinematic MRI...

The aim of this study was to evaluate disc degeneration and kinematic changes in translation and angular motion of the thoracic spine using kinematic MRI (kMRI). 105 thoracic spine kMRI were analyzed from T4-5 to T11-12 using MRAnalyzer3. Translational and angular motion were evaluated in neutral, flexion, and extension positions. Thoracic disc height and disc degeneration grading were measured in the neutral position. Intraclass Correlation Coefficients were used to analyze agreement among three observers. The Friedman's test was used to analyze the difference in disc height, disc degeneration, translational motion, and angular motion. The Wilcoxon-signed rank test was used for post-hoc analysis with a Bonferroni correction. A p-value of 0.00625 was used to establish a statistically significant difference. Analysis using the Friedman's test revealed that translational motion, disc height, and disc degeneration were significantly different from T4-5 to T11-12 (p < 0.001). The T4-5 level showed the least translational motion, while the T10-11 showed the most translational motion. The lower thoracic level (T8-12) showed significantly more translational motion, more advanced disc degeneration, and greater disc height than the upper thoracic level (T4-8, p < 0.001). T11-12 showed the most advanced disc degeneration. There was a significant negative correlation between disc degeneration and translational motion at the upper thoracic level (p = 0.013). The lower thoracic region (below T8) had significantly more translational motion, more advanced disc degeneration, and greater disc height. This information is crucial in further understanding thoracic spinal kinematics and may contribute to determining the stopping level in fusion surgeries involving the thoracic spine.