The Measurement and Clinical Importance of Syndesmotic Reduction After Operative Fixation of Rotational Ankle Fractures.

BACKGROUND Rotational ankle fractures often have unstable syndesmotic injuries that require reduction and stabilization. Multiple studies have focused on methods to assess syndesmotic reduction; however, the clinical importance of anatomic syndesmotic reduction remains unclear. The purpose of this study was to determine whether the quality of syndesmotic reduction influenced clinical outcomes following operative treatment of ankle fractures with unstable syndesmotic injuries. METHODS Patients were included from an institutional trauma registry if they had sustained rotational ankle fractures with intraoperative evidence of syndesmotic instability requiring syndesmotic reduction and stabilization. Patients with at least twelve months of disease-specific, patient-reported clinical outcomes were included. Computed tomography (CT) imaging of both ankles was performed within two days postoperatively for all patients. Four previously utilized methods of assessing syndesmotic reduction using axial CT images of the operatively treated and the contralateral ankle were used. RESULTS A total of 155 patients met the study inclusion criteria and underwent analysis. The four methods used to assess syndesmotic reduction had reliabilities ranging from moderate to almost perfect (intraclass correlation coefficient [2,1] range = 0.544 to 0.821). Measurements of the uninjured syndesmosis were consistent with those in several previous studies of normal syndesmotic morphology, and the four methods of syndesmotic assessment had strong internal consistency. The mean measurement differences between the injured and normal ankles ranged from 1.32 to 1.88 mm of displacement and averaged 5.75° of rotation. There were no correlations noted between any of the four syndesmotic reduction assessment methods and any Foot and Ankle Outcome Score domains. CONCLUSIONS Within the range of syndesmotic malreductions studied, the quality of syndesmotic reduction did not significantly influence clinical outcomes. These results challenge previous definitions of syndesmotic malreduction and the clinical importance of minor syndesmotic changes. It remains unclear, however, whether greater magnitudes of syndesmotic malreduction than those seen in this cohort would lead to inferior patient-reported outcomes.