Abstract
<jats:p>Background. Segmental defects of the tibia (critical defect: more than 2 cm long and loss of more than 50 % of bone mass) are divided into primary (due to high-energy trauma) and secondary, as a result of radical resection of necrotic and infected bone fragments, resection of bone tumors, etc. Within the framework of biomechanical studies of modern fixators, great attention is paid to the development of structural parameters that influence the stability of the construct, such as rigidity, maximum stress values at the control points of the system and performance of the pin-bone interface. The purpose of the study was to investigate the stress-strain state of a model of the lower leg with a tibial defect with different options for its extra-articular osteosynthesis under the influence of a bending load acting in the sagittal plane. Materials and methods. A defect 5 cm long was modeled in the middle third of the tibia. Stabilization of the tibia with an external fixation device was studied with three options for inserting rods with a diameter of 8 mm at angles of 30, 60, and 90°. Results. Under the influence of bending load in the sagittal plane, insertion of fixing rods at an angle of 30° creates a maximum stress in the bone tissue of 13.4 and 9.4 MPa around distal pair of rods, around proximal one — of 8.4 and 6.6 MPa, respectively; at an angle of 60°, compared to the previous model, it causes an increase in the level of stresses in the bone tissue almost around all fixing rods. Change in the distribution of stresses on the fixing rods inserted at an angle of 90°: on rods 1 and 4, the stress level decreases to 48.4 and 28.0 MPa, respectively, which are the lowest indicators for all previous models. Conclusions. With a bending load acting on the limb in the sagittal plane, the most favorable option for minimizing stresses in the bone tissue is the installation of the external fixation device with the fixing rods inserted at an angle of 30°.</jats:p>