MRI Evaluation of Weightbearing Stable Suprasyndesmotic Ankle Fractures

Research Type: Level 2 - Prospective comparative study, Meta-analysis of Level 2 studies or Level 1 studies with inconsistent results Introduction/Purpose: According to Lauge-Hanse, suprasyndesmotic ankle fractures occur in pronation type injuries to the ankle. Because of the expected instability of these fractures, operative stabilization is advised. Recent studies on Weber B fractures have shown that varying degrees of medial injury exist, influencing stability and treatment approach. The deep posterior part of the deltoid complex has been found to play a crucial role in maintaining talocrural stability. A congruent ankle joint on stress radiographs may indicate intact medial stability, suggesting that operative stabilization may not be warranted. However, studies on the ligamentous injuries of suprasyndesmotic ankle fractures that show congruency on weightbearing radiographs are lacking. This study aims to utilize MRI to examine the ligamentous injuries in suprasyndesmotic ankle fractures that appear stable on stress radiographs. Methods: Twenty patients with suprasyndesmotic ankle fractures (Weber C/Maisonneuve) and talocrural congruency on weightbearing radiographs were recruited from Oslo University Hospital and Østfold Hospital, Kalnes. MRI was performed within two weeks of the injury. Two senior musculoskeletal radiologists from both centres assessed the images and scored the ligamentous injuries to the deltoid ligaments and syndesmotic ligaments based on the degree of damage (intact, partial, or complete rupture). In cases of disagreement between radiologists on the degree of damage, a consensus would be reached. Results: We included twenty patients during a period of one year (2023-2024). Mean age was 55 years (22-75). High fibular fractures (Maisonneuve) accounted for 55% of the included injuries. The anterior inferior tibiofibular ligament (AITFL) and intraosseous ligament (IOL) was completely ruptured in 90% (18/20). The posterior inferior tibiofibular ligament (PITFL) and the deep posterior tibiotalar ligament (dPTTL) was completely ruptured in only 10% (2/20). Conclusion: Suprasyndesmotic ankle fractures that show talocrural congruency on weightbearing radiographs tend to have an intact deep posterior tibiotalar ligament and posterior inferior tibiofibular ligament when assessed by MRI. These fractures may retain sufficient stability to be managed conservatively in line with the current approach to stable Weber B fractures, but further clinical studies are needed.