Syndesmotic Reduction Landmarks in Healthy Ankle Patients, Comparative Analysis of Weight- Bearing Computed Tomography

Abstract

Category: Ankle Introduction/Purpose: Introduction: The diagnosis of low-energy syndesmotic injuries continues to be a challenge, and there is no standard for it. Being the dynamic exams, the ones with the best performance. With the development of Weight-Bearing computerized tomography (WBCT), the understanding of their lesion patterns has improved, however, there is high variability in the syndesmotic anatomy between different individuals, with asymmetry parameters in up to 89% of healthy syndesmosis. therefore the best element to evaluate them is the healthy contralateral ankle and compare these parameters. However, what are the normal values in our population, or the possible anatomical differences according to different age groups, in the morphology of the syndesmal notch of our patients, nor that there is a real symmetry between both ankles. Methods: Retrospective analysis of comparative bilateral ankle WBCT in healthy patients from March 2018 to July 2021 according to the parameters: anterior, posterior and central syndesmal distance, fibular rotation, sagittal translation and area. All patients with comparative bilateral ankle weight-bearing CT taken since January 2018 to August 2021, patients without history of ankle injuries, were included in the analysis. That have required a comparative bilateral WBCT to study another pathology. Patients with a history of acute or chronic ankle or syndesmal injuries, patients with degenerative ankle joint injuries, with severe misalignments > 10° in varus or valgus, incomplete or non-comparative study were excluded. Results: 150 patients with comparative bilateral WBCT were evaluated. Among the ankles evaluated with WB CT in a comparative manner, it is established that there were no significant differences between both ankles of subjects with healthy ankles (Wilcoxon Test) in anterior syndesmal distance (SD), posterior SD, central SD, syndesmal area (p > 0.05). While fibular rotation and sagittal translation showed significant differences between the measurements in healthy ankles, evaluated with comparative bilateral WB CT in independent evaluations (p < 0.05). Regarding the differences by age range established for the different syndesmotic reduction parameters, for the different subgroups of patients under 40 years of age, 40 and 60 years of age and over 60 years of age, no significant differences were generated between them (Wilcoxon test). Conclusion: We have established normal ranges for measurements in the syndesmal anatomy in axial slices during weight bearing CT, as well as that there are no differences between the right and left ankle in healthy ankles in anterior, posterior and central syndesmal distance, or syndesmal area. Being these parameters, the most suitable as internal control for patients with suspected syndesmotic injury regardless of the age of the patients.