Models of L4 and L5 vertebrae, sacrum and iliac bones were constructed on the basis of a computer tomogram. The sacrum model was constructed with three types of fractures: outward from the facet joint passing through the facet joint and inward relative to the facet joint. In addition, two main splinters of the sacrum were modeled, as well as screws passing through the iliac bones and elements of transpedicular fixation. Two variants of typical loads were considered: compression load and bending moment, compression load and rotation moment. In the case where screws passing through the iliac bones were combined with transpedicular screws, the maximum displacement in the models (for all three types of fracture) significantly decreased. This allows us to conclude that the variant of fixation with the help of a transpedicular structure makes the model more stable, that is, increases the rigidity of the structure, preventing the fixed elements of the vertebral-pelvic complex from shifting relative to each other. Equivalent stresses in the screws passing through the iliac bones were also reduced when installing the transpedicular structure. In this case, the stresses in the bone tissues did not differ significantly with different types of implants and loading options. Thus, if we evaluate the field of equivalent stresses in the models, a more rational from the point of view of biomechanics is the option of installing a transpedicular system in addition to screws passing through the iliac bones. This will reduce the risk of damage to both the structure and bone tissue.