A set (1, 301, 501) of polyaxial bone screw that includes a spike (4, 304, 504) having an upper portion (8) and a body (6) for fixation in a bone (15), having the upper portion one protruding end (42)； a receiver (10, 310, 510) defining an open channel (56) and a cavity (78) that communicates with the open channel； a retention and articulation structure (12, 320, 520) that holds the upper pin portion in a position relative to the cavity, the protruding end of the pin extending outward beyond the retention and articulation structure when the upper portion it is attached to the retention structure and articulation； and a pressure insert (14, 410, 610) capable of being received in the receiving cavity, the pressure insert having a fitting position in which the pressure insert fits with the projecting end of the spigot during pivoting the pin in relation with receiver in all its positions, so that the pressure insert exerts a downward force exclusively on the projecting end of the spike so that the retention and articulation structure frictionally fits the receiver in an interlocking configuration, characterized in that: a ) the receiving cavity has a seating surface (82) that is partially spherical in shape, the retention and articulation structure has a partially spherical outer surface (104) that is dimensioned and configured to mate, and rotate polyaxially, with the seating surface of the cavity during positioning, and the retention and articulation structure e It is attached to the upper pin portion inside the receiver so that it pivotally rotates with the pin relative to the receiver during positioning.Un conjunto (1, 301, 501) de tornillo óseo poliaxial que incluye una espiga (4, 304, 504) que posee una porción(8) superior y un cuerpo (6) para su fijación en un hueso (15), teniendo la porción superior un extremo (42)sobresaliente； un receptor (10, 310, 510) que define un canal (56) abierto y una cavidad (78) que comunica con elcanal abierto； una estructura (12, 3
