Magnetic resonance imaging-based assessment of lateral ligament injury and soft-tissue swelling in ankle trauma: Correlation and clinical predictive value

Objectives: Magnetic resonance imaging (MRI) can complement clinical evaluation of ankle ligament injuries. This study aims to elucidate the relationship between lateral ligament injury and soft-tissue swelling in patients presenting with ankle injuries devoid of fractures, utilizing MRI. Materials and Methods: A retrospective analysis was conducted over a 1-year period, including 100 consecutive patients diagnosed with ankle injuries unaccompanied by fractures. All patients underwent MRI within 1 week of injury. Soft-tissue thickness surrounding the medial and lateral malleoli was measured on coronal proton density fat-suppressed MRI images. MRIs were further categorized based on the condition of ankle ligaments: normal ankle; isolated anterior talofibular ligament (ATFL) injury; isolated calcaneofibular ligament (CFL) injury; isolated anterior-inferior tibio-fibular ligament (AITFL) injury; combined ATFL and AITFL injury; and combined ATFL and CFL injury. Results: Analysis of the medial/lateral malleolar swelling ratio revealed an area under the curve of 0.636 (95% confidence interval [CI]: 0.500–0.773), indicating moderate discriminatory ability. Isolated lateral swelling exhibited a higher area under the curve of 0.842 (95% CI: 0.756–0.927). A lateral swelling measurement exceeding 2.5 mm demonstrated 91% specificity and 51% sensitivity. Statistical analysis revealed a highly significant association between lateral ligamentous injury and both lateral swelling ( P < 0.0001) and the swelling ratio ( P = 0.0001). Conclusion: Lateral malleolar soft-tissue swelling serves as a valuable predictor of ligamentous injury in ankle trauma cases. MRI provides complementary evidence to correlate the association between the size of lateral soft-tissue swelling and associated ligamentous injury.