Biomechanical investigation of the effects of various treatment options on the talus in supination external rotation type 4 ankle injuries with ruptured deltoid ligament: Finite element analysis

Purpose: The purpose of this study is the biomechanical investigation of the rotation, stress and deformation caused in the talus, under a specific load, by various fixation methods in ankle which has supination external rotation (SER) injury and deltoid rupture. Method: Ankle of a healthy individual was analyzed with the help of a package program which was based on finite elements method (FEM). Then, SER injury model was created. Lateral malleolar plate was fixed with a screw and created different repair models for ankle fit. In the analysis section, forces obtained from the literature were applied to the healthy and repaired models. As the result of the analyses, mechanical values which occured in the talus were obtained. Results: As a result of this study, mechanical changes in talus, which were caused by, (in order) deltoid ligament repair, suture button syndesmosis fixation, syndesmosis fixation with transfixation screw, suture button fixation + deltoid ligament repair and transfixation screw + deltoid ligament repair in the SER type 4 injury model with deltoid ligament rupture, were evaluated. Conlusion: This study showed that the application of syndesmosis screw together with deltoid ligament repair in the treatment of SER type 4 ankle injuries with rupture of deltoid ligament made regression, displacement and talus rotations on the talus almost normal. In addition, syndesmosis fixation screw applications give better results than syndesmosis fixation suture button applications.