A top-loading multi-axial, double locking bone anchor assembly. A receiver member receives an internal saddle member, a bi-polar member, and a bone anchor through an open bottom, which are retained by an internal threaded ring member threaded onto the receiver member. A double-locking compression retaining...http://www.google.fr/patents/US7896902?utm_source=gb-gplus-shareBrevet US7896902 - Multi-axial double locking bone screw assembly
