Isolated posterior malleolus fracture – magnetic resonance imaging diagnosis

Abstract

Approximately 7% to 44% of ankle fractures involve the posterior tibial margin. These fractures tend to have a poorer prognosis than fractures without posterior involvement. Recognition of posterior malleolar fracture patterns is more important than fracture fragment size in decision making. Standard ankle radiographs are not effective for diagnosing isolated posterior malleolar fractures. There is consensus that the true size and geometry of the fragment, specifically its medial propagation, and intercalary fragments may be diagnosed only by computed tomography scanning. Magnetic resonance imaging may yield additional information about syndesmotic ligaments, tendons and osteochondral lesions, although it is used only exceptionally. There are controversies about the treatment of these fractures but authors agree that small fragments can be treated conservatively whereas larger fractures that involve more than 25% of articular surface should be fixed to avoid instability and degenerative changes. The authors report a case with a magnetic resonance imaging diagnosis of this fracture.