Fig. (9) Long-leg standing radiograph six years after femoral and
nine years after tibial lengthening: The frontal plane mechanical
axis, which is drawn from the center of the femoral head to the
center of the ankle plafond, passes slightly medial to the center of
the knee joint indicating an optimal limb alignment. This
perpendicular distance, also called mechanical axis deviation
(MAD), is normally 8±7mm medial to the center of the knee joint.