Аналіз напружено-деформованого стану стегнової кістки за вогнепальних переломів і методики її фіксації

The standard method for stabilizing diaphyseal gunshot fractures of the femur (GFF) is external fixation using a rod apparatus (ex-fix). Objective. To perform a comparative analysis of the biomechanical effectiveness between conventional ex-fix fixation and a modified «ex-fix + intramedullary spacer» design by assessing the stress-strain state of the femur with a midshaft gunshot fracture. Methods. A finite element model of a midshaft femoral gunshot fracture was developed. Two fixation scenarios were simulated: standard rod-based ex-fix, and a combined system using an intramedullary spacer and an ex-fix rod apparatus. Displacement, stress, strain and safety factor were chosen as the effects studied. Results. Conventional fixation resulted in significant stress concentrations at the fracture site (62.4 MPa) and high deformation levels (215.9), exceeding the strength threshold of cortical bone. This may lead to fragment instability and femoral axis misalignment. Rod exit points showed deformation (121,1), contributing to loosening, inflammation in adjacent soft tissues, and overall instability of the fixation system. In contrast, the addition of an intramedullary spacer redistributed stress more evenly, reduced the mechanical load on bone tissue, and improved structural integrity. The combined «spacer + ex-fix» configuration demonstrated superior performance in minimizing deformation and fragment displacement. Conclusions. Finite element modeling confirmed that the «bone + ex-fix + spacer» system outperforms the traditional «bone + ex-fix» configuration in key parameters: displacement, stress, deformation, and safety margin.