Reliability of Radiologic Assessment of the Fracture Anatomy at the Posterior Tibial Plafond in Malleolar Fractures

Abstract

The aim of this study was to assess the ability to extract surgically relevant information from plain radiographs in trimalleolar fractures and to compare this with the information gathered from computed tomography (CT). Retrospective analysis of consecutive patients. Level 1 trauma center. Retrospective analysis of the records of 22 patients with trimalleolar fractures treated at our institution between 1996 and 2006. Inclusion criteria were a complete radiographic documentation including plain anteroposterior and lateral radiographs and a preoperative CT scan of the ankle joint. The radiographs of the included patients were evaluated twice within 3 months by 8 experienced orthopaedic trauma surgeons. The following criteria were analyzed: the presence or absence of a fracture in the posteromedial corner of the tibial plafond, loose posterior osteochondral fragments, impaction of posterior osteochondral fragments on the anteroposterior and the lateral radiographs, and size of the posterolateral fragment as percentage of the articular surface in the capital diameter of the tibial plafond. The results were compared with the CT scans. All parameters showed a poor to fair reproducibility, reliability, and accuracy except the size of the posterior fragment, where good correlations were achieved. Only the extent of the posterior fragment can be measured reliably, reproducibly, and accurately on plain radiographs. Comminution and impaction of the posterior fracture are underestimated by far. Surgically relevant information is missed, which can lead to intraoperative inability to properly reduce the fracture. Preoperative CT evaluation is recommended in all patients with trimalleolar fractures, independent of the size of the posterior fragment.