## 1 Introduction  
Today, medicine is increasingly using engineering solutions to improve and accelerate the treatment process and is successfully applying a multidisciplinary approach to problematic tasks [1, 2, 3, 4]. The consolidation periods of broken shin bones remain long and significantly depend on the choice of correct tactics and method of treatment [5, 6, 7]. The choice of the optimal surgical treatment method for a broken fibula has been debatable for decades [8, 9, 10]. At the same time, concomitant repair of unstable syndesmosis injuriesdoes not have a unified approach. Here, the most common divergence of views on surgical treatment is associated with the use of two conceptually different methods--screw fixation of the syndessmosis and elastic (dynamic) fixation [11]. Injuries of the tibiofibrular syndessmosis are among the most difficult in surgical treatment. This is primarily due to the complexity of the joint-forming structures that accompany not only injured bones, but also the interosseous membrane, ligaments, and the tibiofibrular syndessmosis itself. The problem of complications and the frequency of unsatisfactory results in surgical treatment of the broken bone with tibiofibrular syndessmosis rupture remains relevant [12]. At present, tibiofibrular syndessmosis fixation with a position screw has become widespread. However, the use of this method can lead to a narrowing of the tibiofibrular fork, limited mobility in the tibiofibrular syndessmosis, the development of incongru fluence of the articular surfaces in the supracalcaneal-shin joint, which in turn can cause the development of arthrosis [13]. In addition, premature or accidental axial loading on the injured extremity can lead to rigid structure destruction. The use of a position screw also requires a stepwise surgical interference to remove it [14]. In the case of broken fibula fixation using an extracortical plate to insert a position screw, it is necessary to provide surgical access to the entire length of the extracortical fixator, which is difficult and sometimes impossible to perform during post-traumatic ischemic personifestations, often accompanied by rupture of the distal third of the shin. At the same time, delayed surgical interference does not solve the problem, since it increases the risk of complications and worsens the repositioning conditions. Therefore, osteomeatal synthesis of the broken shin bones with tibiofibrular syndessmosis injury should combine stable fixation of the broken bone and not limit the elastic properties of the syndessmosis [15]. In particular, in the case of a broken fibula, it is proposed to use a stable extracortical fixator (extracortical fixator metal plate) and an elastic connection of the syndessmosis injury with a tightrope, which is attached using Endobutton fixation devices (Figure 1). This approach optimizes the fusion process of the fibula bone and contributes to anatomically correct positioning and adequate elastic restoration of the syndessmosis integrity. In our study, we decided to focus on aspects related to the biomechanics of the injured syndessmosis elastic fixation. To explain exactly how mechanical factors affect the stabilization of various types of ruptures, the classical theory of mechanical stresses and strains, [PERSON]'s strain theory, contact interaction mechanics, etc., are used [16; 17; 18; 19]. The success of the bone plate insertion is assessed depending on its long-term stability, which, in particular, is determined by the biomechanical properties of the bone-plate boundary line. The surfaces of materials are often subjected to various modifications,  
Figure 1: Scheme for stable–elastic fixation of the fibula injury: 1, broken bone; 2, metal plate, 3, elastic tightrope. which improve their physical and biochemical properties and make it possible to obtain the optimal topology of the contact surface [20; 21; 22].