Study of the stress-strain state of models of various options for osteosynthesis of tibia bones with diaphyseal fractures in the middle third in children with imperfect osteogenesis and incomplete growth. Part 2. Torsion

Background. Osteogenesis imperfecta is accompanied by multiple fractures of skeletal bones, the development of progressive deformations of the limb bones and, as a result, impaired support, and walking. The most common mean for stabilizing bone fragments in the treatment of fractures due to osteogenesis imperfecta are intramedullary fixators of various designs. The treatment of this disease requires a long time, therefore, the use of internal fixators without the possibility of their extension during skeletal growth leads to an increase in the frequency of repeated surgical interventions due to the need for their replacement. Goal: to investigate the stress-strain state of the lower leg models under the influence of torsional load in conditions of a fracture of both bones in the middle third and their osteosynthesis using intramedullary rods of various designs in children with osteogenesis imperfecta and incomplete growth. Materials and methods. Mathematical modeling was carried out of two options for osteosynthesis of tibia bones with a fracture in the middle third in children with osteogenesis imperfecta: 1) a rod without rotational stability; 2) a rod with rotational stability. During the research, the stress-strain state of the models under the influence of torsional load was studied. Results. A rod with rotational stability during tibial osteosynthesis allows reducing the stress along the fracture line to 0.3 MPa. In other zones, the stress remains at the same level as when using a rotationally unstable rod. The main advantage provided by a rod with rotational stability in tibial osteosynthesis under the influence of torsional loads is the reduction of the stress along the fracture line to 0.3 MPa, which is important in the treatment of children with osteogenesis imperfecta. Conclusions. Under torsional loads, a rod with rotational stability provides a 10 times lower stress along the fracture line compared to a rotationally unstable rod.