APPLICATIONS OF WEIGHTBEARING CT IN JOINT INSTABILITY

Abstract

Acute syndesmotic ankle injuries continue to impose a diagnostic dilemma and it remains unclear whether weighbearing or external rotation should be exerted rotation during the imaging process. Therefore, we aimed to implement both axial load (weightbearing) and external rotation in the assessment of a clinical cohort of patients with syndesmotic ankle injuries syndesmotic using weightbearing CT imaging. In this retrospective comparative cohort study, patients with an acute syndesmotic ankle injury were analyzed using a WBCT (N= 20; Mean age= 31,64 years; SD= 14,07. Inclusion criteria were an MRI confirmed syndesmotic ankle injury imaged by a bilateral WBCT of the ankle during weightbearing and combined weightbearing-external rotation. Exclusion criteria consisted of fracture associated syndesmotic ankle injuries. Three-dimensional (3D) models were generated from the CT slices. Tibiofibular displacement and Talar Rotation was quantified using automated3D measurements (Anterior TibioFibular Distance (ATFD), Alpha Angle, Posterior TibioFibular Distance (PTFD) and Talar Rotation (TR) Angle) in comparison to a cohort of non-injured ankles.ResultsThe difference in neutral-stressed Alpha° and ATFD showed a significant difference between patients with a syndesmotic ankle lesion and healthy ankles (P = 0.046 and P = 0.039, respectively) The difference in neutral-stressed PTFD and TR° did not show a significant difference between patients with a syndesmotic ankle lesion and healthy ankles (P = 0.492; P = 0.152, respectively).ConclusionApplication of combined weightbearing-external rotation reveals a dynamic anterior tibiofibular widening in patients with syndesmotic ankle injuries. This study provides the first insights based on 3D measurements to support the potential relevance of applying external rotation during WBCT imaging. However, to what extent certain displacement patterns are associated with syndesmotic instability and thus require operative treatment strategies has yet to be determined in future studies.