Vertebral osteosynthesis equipment

This equipment comprises at least one connecting bar and at least one sacrum anchor assembly (1-3, 5). According to the invention, each sacrum anchor assembly comprises two sacral anchor screws (1, 2), a link assembly (3) including: a sacral connecting part (10) assembled to a sacral anchor plate (11) with polyaxiality, i.e. having possible multi-directional tilting relative to the said first screw (1), and possible pivot relative to the said sacral anchor plate (11); two nuts (5) able to be screwed onto the said shanks (9) of the said first and second screws (1, 2), a first nut (5) is able to clamp this part (10) against a bearing surface (8) formed in the said first screw (1), for tilt and pivot immobilisation of this part (10) relative to the said sacral anchor plate (11).