Comparison of Open Syndesmotic Repair and Trans-syndesmotic Screw Fixation: A Biomechanical Study

Abstract

Category: Trauma; Ankle Introduction/Purpose: We hypothesized that open syndesmotic repair for ankle syndesmotic injury would provide adequate strength. The purpose of this study was to compare the biomechanical properties of open syndesmotic repair with those of screw fixation. Methods: Ten matched pairs of human cadaver specimens were subjected to open syndesmotic repair or screw fixation. Each specimen underwent initial intact physiologic loading, consisting of 10 cycles of external torsional loading with a peak torque of 7.5 Nm at 0.05 Hz. Post-fixation cyclic loading consisted of 50 cycles of combined axial and external rotation loading with peak torques of 750 N and 7.5 Nm at a rate of 0.05 Hz. After post-fixation loading, each specimen underwent failure loading by external rotation at 0.25 degrees/second. Failure was defined as a sudden decrease in the torque-degree curve. Failure torque and failure angle were measured. The paired t-test and Wilcoxon signed-rank test were used to analyze the data. Results: Mean failure torques were 95.63 Nm in the open syndesmotic repair group and 108.61 Nm in the screw group. Mean failure angles were 34.93 degrees in the open syndesmotic repair group and 43.55 degrees in the screw group. These data were not statistically significantly different between the two groups (p = 0.7682 and 0.4133, respectively). Conclusion: Open syndesmotic repair for ankle syndesmotic injury provides similar torsional strength to that of screw fixation. Therefore, this technique can be considered as an alternative treatment option for syndesmosis injury.