In the real life, the leg and its skeleton are exposed at the most diverse stresses. It is known that the human bone is one of the most important natural composite materials. The paper presents a method of study and the steps to obtain the virtual bones of the human body, method applied to tibia bone. For that purpose was used a CAD parametric software which permits to define models with a high level of complexity. To obtain the bone cross sections of the tibia bone a Computer Tomograph was used. The obtained 3D model is studied using the finite element method, taking into consideration the real structure of the bone and the mechanical characteristics of cortical and spongy, and we can obtain the stresses distribution for different solicitation.