The subject of unsolved problems of improvement of heel bone osteosynthesis is the search for a simplified technique of biological fixation, which provides minimum trauma to ensure intraosseous stable fixation and reduction risk of infectious complications. To conduct a comparative analysis of the stiffness of fixation of bone fragments in two variants of intraosseous osteosynthesis of ligamentous and impressionistic fractures of the calcaneus. Material and methods. Mathematical modeling of the stress-strain state of the model of the posterior part of the foot with a fracture of the calcaneal bone of the lingual and impression types is carried out. We modeled intraosseous osteosynthesis with spokes, using the proposed method, and chose osteosynthesis with spongy screws for comparison. The models were studied under the influence of actions of an external system of spatial loads. Results and discussion. Analysis of the stress-strain state of the models the rear of the foot showed that the fracture fixation ray spokes leads to uniform distribution of stresses in all checkpoints of the bone elements in the range of 3.3 to 4.5 MPa, under Impressionum – 3.3-5.0 MPa. In the model with fixing fragments with screws, the stress level is slightly higher and was observed, respectively, in the range of 4.5-7.9 MPa and 4.0-7.6 MPa at all control points. Studies of relative deformities in models showed a slight advantage of fixing spokes (0.1-1.7%) compared with screws (0.1-1.9%) in the bone regenerate fracture of the calcaneal bone of both types. The study of the stress-strain state of models of the posterior part of the foot determined that fixation of fragments with spokes allowed to obtain lower values of maximum stresses in the bone elements of the foot and deformities in the bone regenerate than fixation with screws for all studied types of fractures of the heel bone. The stiffness of fixation of bone fragments under the action of an external system of spatial loads in the intraosseous osteosynthesis of the considered types of fractures of the calcaneus by spokes exceeds osteosynthesis by screws by 2.1 times (p˃0.05). Conclusion. The advantage of using spokes after the closed one-movement instrumental reposition performed by H. Westhues (1934) is explained by the fact that despite the repositional nature of intraosseous osteosynthesis, the proposed method stabilizes the fragments of the heel bone due to the fact that one pair of spokes, passing through the fragments of the heel bone, enters the talus, and the other pair of spokes – in the cuboid bone, blocking mobility in the talus-calcaneal and heel-cuboid joints. Additional stability of the fragments of the calcaneus is provided by the talus, calcaneus, and cuboid bones that are bonded together, which prevents the action of the calf muscle, whose contraction usually leads to the displacement of the fragments (a change in the angle of Böhler's).
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