Figure 1.

(a) Traditional measurement method on lateral plain radiographs is shown schematically. The percentage of involved articular surface is ii/i + ii. (b) A case would be excluded if the fracture line could not be identified and therefore measurement could not be performed. Images showed the lateral plain radiograph of a 23-year-old male patient with Lauge-Hansen supination-external rotation type 3 ankle fracture. The patient was excluded because the posterior malleolar fracture line was difficult to be identified on the lateral radiograph. (c) On the sagittal multiplanar reconstruction CT image of the same patient, the posterior malleolar fracture line could be clearly identified. (d) A large difference in the articular involvement of posterior malleolar fractures is shown on the sagittal CT images (3D pseudocolor display mode) selected by different observers.