The photographs of the femoral notch in the axial view and the lateral view. On a photograph taken in the axial view (A), we drew a circle superimposed onto the cylindrical roof and lateral wall around the POIN. Then, we drew a diameter of this circle which was perpendicular to the posterior condyle (PC) line. Then, the center of the red marker was measured with the so-called “clock” system. On a photograph taken in the lateral view (B), we drew a reference line of the femoral shaft (FS) axis. Then, we drew 2 lines, which were perpendicular to the reference line and passing the center of the femoral attachment of the AM mid-substance fibers (a red marker) and the POIN, respectively. A distance between the 2 lines was defined as Distance D.