Evaluation of Fibula and Talus Position in Patients with Chronic Ankle Instability Using Computed Tomography

Background Chronic ankle instability (CAI) is a common sequela of recurrent ankle sprains, yet the role of bony structural changes in its pathogenesis remains debated. This study aimed to evaluate the positional relationships of the fibula and talus in CAI patients using computed tomography (CT). Methods A retrospective cohort study included 50 CAI patients and 50 controls. Axial CT images were analyzed to measure four indices: Axial Malleolar Index (AMI), Intermalleolar Index (IMI), Malleolar Talus Index (MTI), and Midpoint Intermalleolar Index (MIMI). Intra- and inter-observer reliabilities were assessed via intraclass correlation coefficients (ICC). Results Demographic variables (age, gender, BMI) showed no significant intergroup differences. AMI, IMI, and MIMI were comparable between groups ( P  > 0.05). However, MTI was significantly reduced in the CAI group ( P  < 0.05), suggesting potential external talar rotation. Conclusion CT axial imaging revealed no significant alterations in fibular positioning relative to the talus or tibia in CAI patients. The observed decrease in MTI may indicate talar external rotation, warranting further investigation into its biomechanical implications. Level of Evidence: III. (DIAGNOSTIC, Retrospective cohort study)