Purpose of this experimental-prospective study on 35 total knee prostheses is to compare the data related to the bone cuts imposed during surgery using PIGalileo navigator and those really gotten and measured by TC scan examination at follow-up. PIGalileo navigator consists of a photogrammetric infrared camera that links a computer to three reflecting sensories fixed on femur and tibia. At follow-up, all the knees were submitted to a spiral TC analysis making a sequential 3 mm axial scans. In six cases (17%) it has not been possible complete the operation utilizing the navigator. Any statistically significance has been found regarding the mechanical axes of the femur and the tibia, the sagittal rotation of the femur and the horizontal rotation of the tibia. High level of statistical significance has been noted for the horizontal rotation of the femur (intraop: 3.7° extra vs. TC: 0.2° intra; p=.006) and for the sagittal rotation of the tibia (intraop: 6.2° post vs. TC: 3.5° post; p = .003). PIGalileo navigator has shown effectiveness to reproduce bone cuts respect the major axes of the knee but it has been less precise in rotation, mainly for the femoral cut.