Methods of treatment of femoral fractures still remain controversial in adolescent age when the patients are too young for adult-type stabilization. This study examines the possibilities for improving the mechanical parameters of the bone-nail interface in flexible intramedullary nailing.

Mathematical models, which simulate different fractures, have been created by using the finite elements method. The stabilizing construction with two 4,00 mm Ender nails was performed in two versions:

standard divergent “C” configuration (3 points of pressure);

Each version has been tested towards the deforming forces – bending in frontal and sagital plane; torsion and axial loading. Strength coefficient of the nails has been calculated as well as the stiffness of the configuration. The comparative analysis of the results found out that under the angular and torsional forces the mechanical parameters of the two types of configurations are equivalent. However, under axial loading, the divergent “S” configuration shows definitely better mechanical characteristics. The strength coefficient is 30% higher and the stiffness of the configuration is twice as strong. The specific intramedullary cohesion enables more considerable resistance towards the transverse displacement in telescoping of the fragments.

Proceeding from the presented data, it could be considered that the divergent “S” configuration creates much more sufficient length control. Its implementation in axial unstable femoral fractures could enable an earlier mobilization, respectively – an earlier weight-bearing loading.