Diabetes has brought several health problems; one of the most common is the amputation of the lower limb, for which the development of low-cost lower limb prostheses has taken on an important role to allow people with these injuries to continue independently with their lives. This paper proposes developing a transfemoral prosthesis for a 47-year-old patient with a weight of 100kg and a height of 1.80m. The approach shows the kinematic model of the four-bar mechanism of the knee, following the Denavith-Hartenberg method, and the calculation of the knee angle curve and the gait with the help of OpenSim. Consequently, it is shown the design of the parts of the prosthesis done in Autodesk Fusion 360 and their optimization by a lattice in Creo software. Finally, the stress simulations in Ansys with the materials previously selected in CES EduPack are presented.