Does the Level of Syndesmotic Screw Insertion Affect Clinical Outcome after Ankle Fractures with Syndesmotic Instability?

Abstract

Ankle fractures are often combined with syndesmotic instability, requiring reduction and stabilization. However, the optimal level for syndesmotic screw positioning remains unclear. This study aims to evaluate the effect of different syndesmotic screw insertion levels on postoperative clinical outcomes and determine whether an optimal level exists. This retrospective study included data from 43 adult patients with acute closed ankle fractures combined with intraoperative evidence of unstable syndesmotic injuries who underwent open reduction internal fixation from January 1, 2017 to March 1, 2018 according to the inclusion and exclusion criteria. All 43 patients were divided into three groups based on the syndesmotic screw placement level: trans-syndesmotic group: screw level of 2-3cm; inferior-syndesmotic group: screw level <2cm; and supra-syndesmotic group: screw level >3cm. Clinical outcomes were measured at the final follow-up, including the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Olerud-Molander Ankle Score (OMAS), short-form 36-item questionnaire (SF-36), visual analogue scale (VAS) score and restrictions in ankle range of motion (ROM). The relationships between screw placement level and clinical outcomes were analyzed with the Kruskal-Wallis H-test and Spearman correlation analysis. The median follow-up duration was 15months (range, 10-22months). No patients developed fracture nonunion or malunion or experienced hardware failure. The outcome scoring systems showed an overall score for the entire group of 94.91 points for the AOFAS ankle-hindfoot score, 83.14 for the OMAS, 96.65 for the SF-36, 1.77 for the VAS, 9.14° for the restrictions in dorsiflexion, and 1.30° for the restrictions in plantarflexion. There were no significant differences among three groups in clinical outcomes (P > 0.05). Neither the AOFAS score nor OMAS had significant correlations with screw insertion level (P=0.825 and P=0.585, respectively). No postoperative arthritis or widening of the tibiofibular space was observed at the final follow-up. Different syndesmotic screw placement levels appear not to affect the clinical outcomes of ankle fractures with syndesmotic instability. No optimal level was observed in this study. Our findings suggest other clinically acceptable options apart from syndesmotic screw placement 2-3cm above the ankle.