Abstract: The present invention provides a system of instruments for shaping the distal femur and proximal tibia surfaces to receive components of a knee prosthesis for knee replacement surgery. The system references the femur intramedullary channel with a femoral alignment guide to prepare the distal femur that, in turn, is a reference for several cutting guides for sequential attachment to the femoral alignment guide and prepared bone surfaces whereby the prepared distal femur is prepared to a flat surface that is perpendicular to the patient's mechanical axis with bone surfaces adjacent thereto sectioned to surfaces that are at right angles to that distal femur surface with chamfers therebetween to receive the femur component of a knee prosthesis.