Abstract: This invention relates to an ancillary for a spinal osteosynthesis system comprising at least one implant that will be implanted in a spine. The implant comprises accommodation means located approximately along a centreline and that will accommodate at least one rod type connecting element. The ancillary comprises holding means that will cooperate with the said implant, and a manipulation means free to move with respect to the said holding means that will be used to manipulate the said connecting element. The said holding means will be arranged on one side of the accommodation means, and the said manipulation means comprises attachment means that will cooperate with the said implant on the side of the centreline of the accommodation means opposite the accommodation means.

Abstract: Bone screw for osteosynthesis devices comprising a screwing head and a screw-threaded shank having a transition portion having a variable profile between two shank parts of different profiles. The threading has a constant pitch and a constant outside diameter, and includes cutting crests throughout its length, including in the transition region. According to one method for manufacturing this screw, there are machined on the transition portion of the shank threads of decreasing depth up to the end of this transition region, the threads along the transition portion defining truncated, non-cutting crests. There is removed from the threads on the transition portion a sufficient amount of material for converting the non-cutting crests into sharp, cutting crests. This method provides a screw with bone anchorage capability throughout the length of the thread.