Comparison of the Size of the Posterior Malleolar Fragment in Trimalleolar Ankle Fractures Measured Using Lateral Plain Radiography and Three-Dimensional Computed Tomography

ABSTRACT

Purpose@#This study aimed to evaluate and compare the accuracy of the size of the posterior malleolar fragment measured using lateral plain radiography and three-dimensional computed tomography (3DCT) in patients with ankle trimalleolar fractures. @*Materials and Methods@#This study enrolled 80 patients (80 ankles) with ankle trimalleolar fractures and analyzed the size of the posterior malleolar fragments using plain radiography and 3D-CT. The articular involvement of the posterior malleolar fragments was measured as a percentage of the articular surface in the sagittal length of the tibial plafond using lateral plain radiography, and the articular surface area was directly measured using 3D-CT. In addition, we classified the patients into three groups based on the morphology of the posterior malleolar fracture, according to the Haraguchi classification method, and evaluated and compared the accuracy of the size of the posterior malleolar fragments. @*Results@#The mean articular involvement of the posterior malleolar fragments on plain radiography was 27.6% (range, 6.0%-53.1%), which was significantly higher than the mean of 21.9% (range, 4.7%-47.1%) measured using 3D-CT (p=0.004). In the analysis, according to the fracture morphology, the mean difference between the two methods was the largest for type I fractures at 9.1% (range, 1.8%-19.5%) and the smallest for type II fractures at 1.1% (range, –7.7% to 8.8%). @*Conclusion@#The articular involvement of posterior malleolar fragments measured using plain radiography showed low accuracy and significantly higher values than the actual articular involvement. Therefore, careful evaluation using 3D-CT is crucial for accurate analysis and optimal treatment in patients with ankle trimalleolar fractures.