An osteosynthesis system comprising anchoring screws, wherein at least one of the anchoring screws comprises a bone anchoring element with a longitudinal axis AA, comprising a threaded anchoring rod prolonged at the end by a coupling head and a screw head for coupling a connecting element to the bone anchoring element, wherein the screw, comprises a body with a longitudinal axis BB traversed longitudinally by a channel featuring in the lower portion a receiving cavity for receiving the coupling head of the anchoring element, at least one connecting element designed to interconnect the anchoring screws, means of tightening the connecting element on each anchoring screw, a means of straightening the bone anchoring element in relation to the screw head during tightening, wherein the means of straightening are arranged to straighten the threaded rod of the bone anchoring element and place the former in the longitudinal axis BB.
