Authors relief importance, from anatomic and functional point of view, of the 1st phalanx's base safety as muscular insertion of all 1st digital ray's short muscles; its elimination gives decrease of big toe's flexion power and instability; on the other hand, articular surfaces are mostly degeneration less. Previous statement to functional balance is examination of muscular function of the 1st digital ray, especially the action of the big toe's adductor and abductor muscle; this is the most important structure to oppose the strength in valgus. The most important surgical acts are: 1) wide dorsimedial approach to the 1st metatarso-phalangeal joint; 2) safety of dorsimedial nervous-vascular structures; 3) medial "Y" capsulotomy and exposure of the 1st metatarso-phalangeal joint; 4) minimal resection of medial hyperostosis; 5) wide transversal lateral capsulotomy and dissection of the big toe's adductor muscle's phalangeal head, and release of the adhesions among metatarsus, lateral sesamoid and lateral capsule; 6) correction of the dislocation of head of metatarsus in relation to sesamoid and correction of the valgus of the big toe; 7) medial capsuloplasty anchoring abductor muscle's tendon, before mobilized, to distal capsular flap. Elective indication of this surgical treatment is essential hallux valgus not structured.