Prediction of distal tibial articular extension in tibial shaft fractures: both posterior malleolar fracture and non posterior malleolar fracture intra-articular extension

Background Multiple authors have highlighted the increased incidence of occult posterior malleolar fractures (PMFs) with spiral tibial shaft fractures, although other reported associated risks of intra-articular extension have been limited. The aim of our study is to investigate both PMFs and non-PMFs intra-articular extensions associated with tibial diaphyseal fractures to try to determine any predictive factors. Methods We undertook a retrospective review of a prospectively collected database. The inclusion criteria for this study were any patient who had sustained a diaphyseal tibial fracture, who had undergone surgery during the study period and who had also undergone a CT scan in addition to plain radiographs. The study time period for this study was between 01/01/2013 and 9/11/2021. Results Out of 764 diaphyseal fractures identified, 442 met the inclusion criteria. A total of 107 patients had PMF extensions (24.21%), and a further 128 patients (28.96%) had intra-articular extensions that were not PMF's. On multivariate analysis, spiral tibial fracture subtypes of the AO/OTA classification (OR 4.18, p < 0.001) and medial direction of tibial spiral from proximal to distal (OR 4.38, p < 0.001) were both significantly associated with PMF. Regarding intra-articular fractures, multivariate analysis showed significant associations with non-spiral (OR 4.83, p < 0.001) and distal (OR 15.32, p < 0.001) tibial fractures and fibular fractures that were oblique (OR 2.01, p = 0.019) and at the same level as tibia fracture (OR 1.83, p = 0.045) or no fracture of the fibular (OR 7.02, p < 0.001). Conclusion In our study, distal tibial articular extension occurs in almost half of tibial shaft fractures. There are very few fracture patterns that are not associated with some type of intra-articular extension, and therefore, a low threshold for preoperative CT should be maintained.