Comparison of Suture-Button Fixation with Suture-Tape Augmentation and Trans-Syndesmotic Screw Fixation for Syndemosis Injury: A Biomechanical Study

CATEGORY: Ankle; Basic Sciences/Biologics INTRODUCTION/PURPOSE: The treatment of syndesmotic injuries with ankle fractures is controversial. The purpose of this study was to compare the biomechanical properties of suture-button fixation with suture-tape augmentation with those of screw fixation. METHODS: Ten matched pairs of human cadaver specimens were subjected to suture-button fixation with suture-tape augmentation or screw fixation. Each specimen underwent initial intact physiologic loading, consisting of 10 cycles of axial loading with peak of 750N, 10 cycles of external torsional loading with peak of 7.5Nm, and 10 cycles of combined axial and external torsional loading with peak of 750N and 7.5Nm at 0.05 Hz. Injuries of the anterior inferior tibiofibular ligament, tibiofibular interosseous membrane, posterior tibiofibular ligament and medial malleolar fracture were applied to each specimen. Postfixation cyclic loading consisted of 50 cycles of combinedaxial and external rotation loading with peak torques of 750 N and 7.5 Nm at a rate of 0.05 Hz. After postfixation loading, each specimen underwent failure loading by external rotation at 0.25 degrees/second. Failure torque and failure angle were measured. RESULTS: Mean failure torques were 15.99 +- 8.88 Nm in the suture-button fixation with suture-tape augmentation and 17.10 +- 10.38 Nm in the screw group. There was no significant difference in average failure torque between two groups (p-value = 0.669)Average failure angle in screw-fixation group (39.37 +- 10.19 deg) was significantly lower than average failure angle suture- button fixation with suture-tape augmentation (56.64 +- 9.64 deg) (p-value = 0.001).Average rotational stiffness in screw-fixation group (0.53 +- 0.24 Nm/deg) was significantly higher than average rotational stiffness in suture-button fixation with suture-tape augmentation group (0.35 +- 0.19 Nm/deg) (p-value = 0.033). CONCLUSION: Suture-button fixation with suture-tape augmentation for ankle syndesmotic injury provides similar torsional strength to that of screw fixation and has lower stiffness than screw fixation. Therefore, Suture-button fixation with suture-tape augmentation can be considered as an alternative treatment option for syndesmosis injury.