An osseous anchorage implant comprising an attachment structure adapted to receive and be attached to at least one bar, that is suitably an element of an osteosynthesis. The implant is made up of an osseous anchor and an attachment head bearing the attachment means. The attachment head is suitably traversed by a channel that is adapted to receive the bar. The attachment head comprises a clamp that is adapted to clamp the bar against an inside support wall of the channel. The implant is further characterized by the attachment means and the support wall enabling the rotation of the bar about a first axis that is not parallel to the longitudinal axis of the bar. The clamp comprises a moving clamping face, that is adapted to contact the bar, and that is borne by a support head that is articulatable at the end of the clamp via a ball and socket connection. The channel is suitably an open channel having an aperture opening onto one of the lateral faces of the attachment head, wherein the aperture bears the clamp. The bar is enabled to be introduced into the channel from a side of the channel.
