Distal Tibiofibular Syndesmosis: Anatomy, Biomechanics, Imaging Approach, and Postoperative Evaluation

The distal tibiofibular syndesmosis is a complex, predominantly fibrous joint comprised of the distal tibia and fibula and a stabilizing complex of ligaments that create a mortise for the talus, thereby facilitating controlled ankle motion. Syndesmotic injuries occur in approximately 10% of sprains and ankle fractures and are commonly caused by rotational trauma, particularly supination-external rotation and pronation-external rotation mechanisms. Radiography serves as the first-line imaging modality for assessment of syndesmotic injuries, helping to evaluate for fracture and disruption of the distal tibiofibular joint. Comparative weight-bearing ankle radiographs, including anteroposterior, lateral, and mortise views, aid in diagnosis; however, MRI is the reference standard for evaluating ligament integrity due to its high sensitivity and specificity. Nevertheless, radiographs and MR images have limitations. Emerging modalities such as stress comparative CT and weight-bearing CT offer promising advancements, yielding images that simulate physiologic loading conditions, improving the detection of subtle syndesmotic instability, and refining diagnostic accuracy. Management strategies are based on the extent of ligamentous injury, bone fracture, and instability. Patients with stable lesions are generally treated conservatively, while those with unstable injuries require surgical intervention. The authors discuss the injury mechanisms, imaging techniques, clinical implications, and management of tibiofibular syndesmotic injuries, with a special focus on emerging imaging modalities, to provide radiologists with a comprehensive guide for accurate evaluation of these lesions. ^©RSNA, 2026 Supplemental material is available for this article.