Mathematical modeling of osteosynthesis options for the lower leg with a multifragment fracture of the proximal end of the tibia under the influence of bending load in the frontal plane

Background. Given the shortcomings of conservative treatment, especially in young patients with multifragment fractures, the surgical method is the priority direction. Internal fixation can be achieved through a variety of designs, both single screws and plates, to provide absolute stability to support the articular surface. Double plate fixation is considered the gold standard, but recent studies using single and double plates have not found significant differences between groups. In addition, the overall rate of postoperative complications with double fixation, according to various authors, is about 11.4 %. Objective: to investigate the stress-strain state of a model with different variants of osteosynthesis of the lower leg with a multifragment fracture of the proximal end of the tibia under the influence of a bending load in the frontal plane. Materials and ­methods. A basic finite element model of the lower leg was developed, which included the tibia and fibula. A multifragment fracture was modeled at the proximal end of the tibia by dividing it into different planes. Three variants of osteosynthesis with bone plates were studied: on the medial, lateral side, and 2 plates on both sides. The models were investigated under the influence of bending load in the frontal plane. Results. Under the influence of bending loads in the frontal plane, osteosynthesis with two plates provides the lowest level of stresses in the bone elements of the model. The exception is the bone fragments in the fracture zone, in which the stresses around the screws from the lateral side have the highest values. As for models with unilateral fixation of fragments, the fundamental differences are also determined in the level of stresses on the bone fragments around the fixing screws, where they differ almost 8 times not in favor of the lateral location of the plate. Conclusions. Under the influence of bending load in the frontal plane, osteosynthesis with two plates provides minimal stress in both the bone elements of the model and the elements of the metal structure, except for stresses in the bone fragments around the screws from the lateral side in the metaphyseal zone. The stresses in models with unilateral fixation of fragments fundamentally differ only in the level of stresses on the bone fragments around the fixing screws, where they differ almost 8 times in favor of the medial location of the plate.