MRI of Isolated Distal Fibular Fractures with Widened Medial Clear Space on Stressed Radiographs: Which Ligaments Are Interrupted?

OBJECTIVE: Patient management choices in ankle fractures remain controversial because of ambiguities in assessing ankle stability and lack of information on the integrity of all supporting ligaments. Our objective was to use MRI to identify the range of ankle ligament injuries associated with a problematic subset of ankle fracture: isolated fibular fractures for which widened medial clear space is absent or minimal on standard ankle radiographs but evident on stress images. CONCLUSION: In our retrospective study of 19 patients, we have categorized ligament injury and found partial or complete tears in all cases in at least two of the four major ligament groups--usually the deltoid and syndesmosis groups. The anterior inferior tibiofibular ligament of the syndesmosis suffered complete interruption in every case. The posterior tibiotalar ligament of the deltoid group, a major contributor to stability, was generally injured but, unexpectedly, most of these tears were partial.