The original technique of Recaredo Alvarez (1972) was reproposed by Pisani (1979) who modified the end orthosis and its position. The original cortical pin was replaced by a spongy bone pin with a cross groove at the proximal end in which to fit the screwdriver. The mid-section is square so that a spanner can be used to adjust it in situ. The distal section is threaded in the normal way. Rather than running from the floor of the tarsal sinus to the neck of the astragalus in the traditional manner, the pin is implanted in the dorsoplantar, proximodistal direction so that the floor of the sinus laces the lateral process of the astragalus. As a result, under load, in addition to the risis that occurs on pronation of the calcaneus we obtain a rotation on the astragalus that acts as a fulcrum for the interosseus ligament thus de-adducting the astragalus itself.