Variability in Syndesmotic Screw Angles During Ankle Fracture Fixation: Insights From Postoperative CT Analysis

TL;DR

This study finds that actual screw angles in ankle fracture surgeries often differ from recommended guidelines and that lower angles may lead to better outcomes.

Contribution

The study provides empirical evidence on the variability of screw angles and challenges the necessity of current fixation angle guidelines.

Findings

72% of patients achieved good syndesmotic reduction after surgery.

Posterior screw placement was significantly linked to poor reduction outcomes.

Lower screw angles (~15°) were associated with better reductions than the recommended 30°-45°.

Abstract

Background

Syndesmotic screw fixation is a widely used technique for stabilizing ankle fractures with syndesmotic disruption. While current guidelines recommend screw insertion at an angle of 30°-45° relative to the anterior foot, limited evidence supports whether these angles are routinely achieved in clinical settings or are necessary for optimal outcomes. This study aimed to assess the angles actually obtained in practice and to identify radiographic factors associated with successful syndesmotic reduction.

Methods

This retrospective study evaluated 100 patients treated with syndesmotic screw fixation for ankle fractures at a secondary referral hospital. Postoperative CT scans were used to assess screw angle, tibiofibular distances, and the quality of syndesmotic reduction. All angle measurements were taken in the neutral ankle position using the second metatarsal head as a reference. Associations between screw trajectory and reduction parameters were analyzed using IBM SPSS Statistics for Windows, Version 29.0.2.0 (Released 2022; IBM Corp., Armonk, NY, USA) and WinPEPI software.

Results

Of the 100 patients, 72% achieved a good syndesmotic reduction. Demographic variables (age, sex), side of injury, injury mechanism, and number of screws showed no significant impact on reduction quality. However, posterior screw placement was significantly associated with poor reduction (p = 0.013). Patients with poor reductions demonstrated significantly higher anterior and posterior tibiofibular distances, greater diastasis, and steeper screw angles (p < 0.001).

Conclusions

There is a notable discrepancy between the recommended and actual screw angles achieved in practice. Lower angles (~15°) were associated with favorable reductions, challenging the necessity of adhering to the 30°-45° guideline. Further prospective studies are needed to refine surgical recommendations based on clinical outcomes.

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