Malreduction of syndesmosis--are we considering the anatomical variation?

Previous studies have demonstrated the need for accurate reduction of ankle syndesmosis. Measurement of syndesmosis is difficult on plain radiographs. A computed tomography (CT) scan allows better visualisation of the transverse relationship between the fibula and incisura fibularis. The difference ('G' a term we coined for ease of description) between the fibula and the anterior and posterior facets of the incisura fibularis was compared between normal and injured ankles following syndesmotic fixation in 19 patients. The mean diastasis (MD) was also calculated, representing the average measurement between the fibula and the anterior and posterior incisura. When compared with the normal side, eight out of 19 (42%) cases were found to have a residual diastasis even after fixation across the syndesmosis. However, if a standard value of G (2mm) was used for the injured leg only, all of the 19 cases would have abnormal values of 'G' following reduction. Our study has clearly demonstrated the need for individualising the assessment method to guide surgeons and radiologists prior to revision surgery. A standard value of 'G' of 2mm as the normal limit cannot be applied universally, as apparent from the data presented in this study.