A polyaxial bone anchoring system comprises a bone anchoring member provided with a hemispherical head and a tubular barrel comprising a base traversed by an axial channel of which the cross-section is greater than the cross-section of the hemispherical head, the channel having, in the lower part, a frustoconical housing that widens in the direction opposite the hemispherical head and, upstream from the frustoconical housing, a transverse shoulder of which the inner cross-section is substantially equal to the cross-section of the hemispherical head, the system further comprising a conical split ring of which the outer surface matches the inner surface of the frustoconical housing and of which the minimum cross-section when idle is smaller than the nominal cross-section of the hemispherical head, said ring being made from a deformable material.
