The Authors repropose the examination pressopoclostatie-X-ray introduced by Pisani in 1973 with wich the foot can be studied as a biomechanic functional entity. From this study it is evident; the fourth metatarsal has paramount biomechanic function; the foot is subdivided anatomofunctionally into calcancus-foot and talar-foot; the variability of metatarsal load formula relative to the different forefoot biomechanics. Furthermore they present the concept of "coxa pedis" and of biomechanic eversion and inversion with the "pivot" function of the talocalcaneal ligament. Finally the Authors emphasize the interdependence between hip, knee and foot.