Biomechanical comparison of different fixation methods for tibiofibular syndesmosis injuries: a finite element analysis study

Syndesmosis injuries require effective fixation to restore ankle stability and function. Therefore, the aim of this study was to use the finite element method to evaluate and compare the biomechanical efficiency of three different fixation techniques used to treat syndesmosis injuries: ANK nails, cortical screws, and suture buttons. A three-dimensional model of the ankle complex of a healthy individual was created from computed tomography (CT) images for finite element analysis (FEA). In the model, the tibia, fibula, talus, calcaneus, and navicular bones and ligament structures were modeled according to anatomical data. Sikka stage-4 syndesmosis injury was simulated by removing the anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), transverse tibiofibular ligament (TTFL), interosseous ligament (IOL), and deltoid ligament. Eight different implant configurations were modeled for fixation, which included ANK nails, cortical screws, and suture buttons. During loading, compressive and tangential forces were applied to the tibial plateau by simulating the midstance phase of gait. Lateral and posterior fibular translation, external rotation, and the joint reaction force (JRF) were evaluated. Compared with the intact model, the lateral translation and external fibular rotation were more restricted by the use of two screws, whereas posterior fibular translation was more restricted by the use of the ANK nail. The screw and ANK nails provided rigid fixation, whereas the suture button allowed flexible fixation. The rigid fixation methods resulted in a more pronounced increase in JRFs. Anatomical suture-button (ANSB) fixation achieved the closest biomechanical parameters to those of the intact ankle model. In the treatment of syndesmosis injuries, ANSB fixation stands out as a method that balances stability with natural joint motion. While rigid fixation methods lead to high joint reaction forces, the ANSB model provides advantages in terms of long-term joint health by providing better preservation of physiological mobility.