A tightening screw for osteosynthesis, including a screw thread that is arranged along a main axis, and including, at its distal end, a recess that has regular shapes about the main axis which are distributed angularly and are suitable for receiving complementary shapes of a screwdriver engaging therewith； the rear face of the screw is inclined in relation to a transverse plane of the screw, the screw being characterized in that the recess in the screw includes at least one specific shape that is different from the other, regular shapes.
