A diagnostic algorithm for acute syndesmotic injuries or ”high ankle sprains”: history, physical findings and imaging

Background: The distal tibiofibular syndesmotic complex is essential for talocrural joint stability, yet isolated injuries remain challenging to diagnose due to the low accuracy of physical examinations and standard radiography. Failure to identify and treat these "high ankle sprains" can result in chronic instability, persistent pain, and secondary osteoarthritis. Objective: This article aims to provide a comprehensive review of syndesmotic anatomy, evaluate the diagnostic efficacy of clinical and imaging modalities, and present an algorithmic approach to therapeutic management. Key Points: The syndesmosis comprises the anterior-inferior tibiofibular, posterior-inferior tibiofibular, interosseous, and inferior transverse ligaments. Clinical tests, including the external rotation stress, squeeze, and Cotton tests, demonstrate variable reliability, with the external rotation test showing the highest inter-rater reliability (0.73–0.74). While standard radiographs have high specificity (0.98) but low sensitivity (0.53), MRI and CT offer superior diagnostic accuracy; MRI sensitivity and specificity for ligamentous tears reach 93–100%. Arthroscopy remains the diagnostic gold standard. Management of stable Grade I and II injuries is typically conservative, involving protected weight-bearing and functional rehabilitation. Conversely, Grade III injuries or those with demonstrated instability require surgical stabilization using syndesmotic screws or suture-button constructs to restore the physiological envelope of motion. Conclusion: Accurate diagnosis of syndesmotic injuries requires integrating patient history, combined physical examination maneuvers, and advanced imaging. An algorithmic approach utilizing MRI or arthroscopy is recommended to prevent long-term sequelae associated with missed syndesmotic instability.