Mathematical modeling of the osteosynthesis of the lower leg bones using a titanium mesh for their congenital pseudoarthrosis in the lower third

Background. Congenital pseudarthrosis of the lower leg bones belongs to the group of orphan diseases and manifests itself in non-union (pseudarthrosis) of the lower leg bones, which leads to the formation of deformity and shortening of the limb, and, as a result, is accompanied by a persistent violation of the limb’s supportability. To date, the question of choosing a surgical technique and optimal fixation in the surgical treatment of congenital pseudarthrosis of the lower leg bones remains unresolved. The purpose was to investigate the stress-strain state of the shin model with pseudarthrosis of its bones in the lower third during their osteosynthesis using a titanium mesh. Materials and methods. Osteosynthesis was simulated with an intramedullary nail, wires, and a block of bone grafts on both shin bones with the imposition of a titanium mesh over the grafts under the influence of two types of compression and torsion loads. Results. Studies have shown that additional fixation of the bone graft block with a titanium mesh allows reducing the stress level at almost all control points of the model of osteosynthesis of the lower leg bones in their congenital pseudarthrosis, both under compression and torsion. As the most positive changes, we can note a decrease in the stress values on the tibia around the nonunion line. This can be explained by the fact that the bone graft block reinforced with a titanium mesh takes on a great load. The same fact contributes to the increase in the level of stress at the lower border of the graft block and tibia. The negative factors include an increase in the level of stress along the line of non-union of the fibula. This is also explained by an increase in the modulus of elasticity of the bone graft block, which further loads the fibula. Conclusions. The use of a titanium mesh for additional fixation of the shin bones in the treatment of their congenital pseudarthrosis has a positive effect on the stress-strain state of the model, which is confirmed by a decrease in the stress level at almost all control points of the model, both under compression and torsion loads. The most positive changes are observed along the line of non-union of the tibia.