The article discusses the use of mathematical modeling by the finite element method to predict the destruction of the flat bones, when exposed to a bladed weapon for introduction and extraction of the blade of the knife into the bone. The simulation showed that the concentration of equivalent stress on top depends on the magnitude of the applied forces, and clearly corresponds to the simulated tilt of the blade, which is fully confirmed by the data obtained in the macroscopic study of stab injuries of the flat bones.