Teixeira PAG, et al. - In this preliminary study, researchers compared quantitative kinematic 4-D CT parameters between healthy volunteers and patients with joint stiffness or chronic ankle instability. For this analysis, 13 healthy volunteers with no previous ankle trauma, 18 patients with clinical subtalar joint stiffness and 10 patients with chronic ankle instability diagnosed on the basis of clinical and imaging findings were evaluated with 4-D CT prospectively. The axial and coronal talocalcaneal angles of healthy volunteers and patients with joint stiffness had statistically significant differences. Data reported that the best sensitivities and specificities for identifying subtalar joint stiffness were 92–100% and 74–94%. Findings suggested that quantitative analysis in 4D CT can provide objective criteria for distinguishing healthy volunteers from patients with subtalar joint stiffness and chronic ankle instability.