Comparative CT Study on Syndesmosis Mobility after Static or Dynamic Fixation for Ankle Fractures with Syndesmotic Rupture: A Pilot Study

Abstract

Background: The objective of this prospective randomized pilot study is to compare, by computed tomography (CT), the mobility of syndesmosis after static fixation (SF) or dynamic fixation (DF) in ankle fractures with syndesmotic rupture (AFSR) in adults, and to compare this mobility with that of healthy ankles.Methods: Forty-two patients with an AFSR were randomized to 2 groups: SF (N=21) or DF (N=21). Seven patients were lost to follow-up. Ultimately, 35 patients (SF, N=20; DF, N=15) were analyzed. The clinical results were assessed with the American Orthopedic Foot and Ankle Society scale. To assess syndesmosis mobility, CT in 30° of plantar flexion (PFlex) and 20° of dorsal flexion (DFlex) was performed on both ankles one year after the fracture. Four parameters were measured: anterior tibiofibular distance, posterior tibiofibular posterior distance, angle of fibular rotation (AFR), and anteroposterior fibular translation. Results: The AFR between DFlex and PFlex was more similar to the non-affected side in the DF group. The other three parameters showed no statistical differences between types of fixation. The mean loss of AFR compared with the non-affected side was 1.2° in the SF group and 0.1° in the DF group. No clinical differences between the SF group and the DF group were found. No correlation between clinical and radiological results was observed.Conclusions: The AFR was more similar to the non-affected side in the DF group. However, this finding did not correlate with a better clinical result. Keywords: Ankle; Fracture; Syndesmosis mobility; Static fixation; Dynamic fixation; CT scan Level of Evidence II: Prospective cohort study.