LAUSR

OBJECTIVES To evaluate the relationship between syndesmosis reduction and outcome. DESIGN Level III diagnostic study. SETTING One level 1 and one level 3 Trauma Centre. PATIENTS Ninety-seven patients with syndesmosis injury. INTERVENTION Stabilization of syndesmosis injury. Open reduction and internal fixation of malleolar fracture, if present. MAIN OUTCOME MEASUREMENTS Anterior, central and posterior measures of syndesmosis width on CT scans, Olerud Molander score (OMA), American Orthopaedic Foot and Ankle Society ankle-hindfoot score (AOFAS) and range of motion (ROM) measurements. RESULTS Eighty-seven patients completed 2 years follow-up. The difference in anterior tibiofibular distance (aTFD) between injured and non-injured ankle postoperatively had a significant effect on OMA-score after 6 weeks (b=-2.6, 95% CI -4.8 to -0.4; p=0.02), 1 year (b=-2.7, 95% CI -4.7 to -0.8; p<0.001) and 2 years (b=-2.6, 95% CI -4.6 to -0.6; p=0.009), and on AOFAS after 6 weeks (b=-2.2, 95% CI -3.7 to -0.7; p=0.004), 1 year (b=-1.7, 95% CI -3.0 to -0.4; p=0.04), and 2 years (b=-1.9, 95% CI -3.2 to -0.5; p=0.006). The effect of CT measurements on ROM were inconsistent. Receiver operating characteristic (ROC) curves demonstrated that aTFD had adequate discriminatory performance (AUC≥0.7) 1 and 2 years after surgery, and the central measurement at only 2 years after surgery. ROC-analyses indicate a cut-off value for syndesmosis malreduction of 2 mm. Postoperative rate of malreduction was 32%. CONCLUSIONS The aTFD correlated with clinical outcome. A 2 mm difference in aTFD seems to predict poorer clinical outcome.