 The knee prosthesis is a validated treatment for end-stage of knee osteoarthritis, and this intervention usually provides a significant improvement in the quality of life of patients. However, a significant percentage of patients up to 30 are disappointed with the outcome of the intervention. One hypothesis that could explain these poor results might be the poor positioning of implants. Individual cutting guides are produced after a CT scan response planning carried out according to the CT scan anatomy of each patient, and subsequently adapted to its real anatomy during surgery, thus theoretically better accuracy of the implementation over conventional techniques. It has been shown in the past that the navigation has been the gold standard in measuring the three-dimensional orientation of the implants during surgery, and this system is systematically used in the service for over 10 years. 