Finite element analysis of titanium cable tensioning ring fixation in the treatment of distal tibiofibular syndesmosis injury

This study employs the finite element analysis method to compare the biomechanical differences between 2 different internal fixation techniques: the novel surgical approach of using titanium cable tensioning ring for distal tibiofibular syndesmosis (DTS) injuries and the conventional method of utilizing Endobutton plate. Utilizing a CT image of the ankle joint from a healthy adult, models representing a normal ankle joint (Model A), a DTS injury (Model B), a titanium cable tensioning ring (Model C), and an endobutton plate fixation (Model D) were developed through finite element software. The Von Mises stress and fibula displacement relative to the tibia were assessed in each model across 3 loading conditions: standing on 1 leg, ankle internal rotation, and ankle external rotation. Across 3 loading conditions, Model B exhibited the greatest displacement of the fibula compared to Model A, with a maximum rate of increase of 166.3% for anterior and posterior displacement, and 265.7% for internal and external displacement. The fibula displacement rates relative to the tibia in Models C and D were below 20%. Additionally, Model B showed the highest maximum stress on the tibiotalar joint surface, increasing by 42.1%, 41.2%, and 35.0% when standing on 1 foot, pronating inward, and pronating outward, respectively. Conversely, the increase in maximum stress on the tibiotalar joint surface in Models C and D was <5%, resulting in a significant reduction of stress on the tibiotalar joint surface following DTS injury. The results showed that high efficacy in treating DTS injuries was demonstrated by the titanium cable tensioning ring, comparable to the effectiveness of an endobutton plate.