Abstract: A surgical treatment system comprises a drill bit extending along a proximo-distal drill bit axis suitable for drilling a hole in the pedicle of a vertebra when the bit is rotated. The bit includes, successively along the drill bit axis, a distal end, a cylindrical drill centred on the drill bit axis for drilling the hole by cutting into and removing bone material from the pedicle to give a distal end portion of the hole a cylindrical shape, and a milling cutter for cutting bone material from the pedicle of the vertebra to give a proximal end portion of the hole a funnel shape gradually widening from the distal end portion of the hole. A pedicle screw extends along a proximo-distal screw axis and is designed to be screwed into the hole by being rotated after the drill bit has drilled the hole and has been removed from this hole.