US Patent 10335203 Polyaxial screw for surgical implant

A polyaxial screw for surgical implant comprising an axially hollow central body; an anchoring element having an anchoring portion and a coupling portion, said anchoring portion projecting from said central body and said coupling portion being received inside the axial cavity of said central body; an insert axially received inside said axial cavity of the central body and an attachment element suitable to couple internally to said central body, characterized in that said insert has an elastic portion able to apply to at least a portion of the anchoring element a distributed compression load the resultant force of which being directed along the central axis X.