In this paper, the results of a biomechanical comparative study using the strain gauge technique are presented. The aim of the study is to emphasize the optimization of the mechanical factors influence in the process of primary callus sedimentation in the focus of a tibial fracture, operated using a Kuntscher centro-medullar nail osteosynthesis. The smaller values of the experimentally determined stresses in different zones of the tibial diaphysis after mounting the nail on the medullar canal show that a part of the load is taken over by the nail. In this way, one can appreciate that the level of the compressive stresses produced in the focus of the fracture is approaching the most favorable one, helping the process of recovery of the bone tissue and quick healing of the patient