A femoral component of a knee prosthesis comprises a femoral flange from an inner end of which extend lateral and medial condylar parts which are interconnected by a box-like bridging part at an intercondylar groove. The interior surface of the femoral component has six discrete flat sections, with the sixth flat section which extends to a free end of the femoral component being angled relative to a plane normal to the third flat section and to the length of the intercondylar groove. Also disclosed is a trial femoral component and a method of use thereof to prepare a femur for the fitting of the femoral component of the prosthesis.