An instrument and method for determining the location of the anatomical epicondylar axis between the condyles of a femur is provided. The instrument includes first and second gauges each for measuring a radius of a femoral condyle and a frame. At least one of the gauges is movably connected to the frame. The method includes positioning the measuring end of each gauge against a separate condyle of a femur, actuating a pivoting member of each gauge to determine the radius of each condyle, measuring the distance between the condyles, and determining the location of the anatomical epicondylar axis of the femur. A measurement can be taken from a measuring scale provided on the gauge and from another scale provided on the frame. Determining the location of the axis can further include performing a calculation utilizing the radii of the condyles and the distance between the condyles.