A bottom-loading multi-axial bone anchor apparatus is disclosed. The apparatus includes a receiver member, a crown member, a bone anchor and a retaining member. The receiver member defines an upper opening and a lower opening, which may form part of the same opening, a channel, and a groove. The crown...http://www.google.fr/patents/US6280442?utm_source=gb-gplus-shareBrevet US6280442 - Multi-axial bone screw assembly
