X-ray features to predict ankle fracture mechanism

Abstract

Introduction: The genetic Lauge-Hansen classification has been traditionally used for reconstruction of the mechanism of ankle injury. The ability of the Lauge-Hansen classification to predict actual mechanism of the injury has been questioned in recent studies, leaving a void in medicolegal reasoning. The aim of this study is to identify morphologic features of malleolar fractures on plain X-rays that may be used to reveal the fracture mechanism.

Material and methods: Radiographs of 78 patients with acute malleolar fractures were analyzed and compared with fracture mechanisms reported by these patients.

Results: A modified Pankovich classification of medial malleolus fractures and the presence of a posterior malleolus fracture were able to significantly predict the mechanism of fracture reported by the patient (p<0.05). Lateral fracture morphology was not useful for predicting the fracture mechanism except for infrasyndesmotic fractures pointing to a supination mechanism.

Conclusion: A supination mechanism of the fracture can be predicted by observing pure ligamentous or chip-avulsion deltoid injury. The presence of an anterior colliculus fracture of the medial malleolus is correlated with a pronation mechanism. A fracture of the posterior malleolus correlates with pronation while an intact posterior malleolus correlateds with supination as a fracture mechanism. Absolute determination of fracture mechanism from the X-ray morphology of the fracture is impossible in the majority of cases.

Keywords: Accidents; Ankle fractures; Classification; Trauma; X-ray.