The invention provides an osteosynthesis and compression screw that is self-boring and self-tapping for the purpose of coaptation of small bone fragments. The screw comprises: a proximal portion formed by a screw head provided with an outside thread; an intermediate portion having no thread; and a distal portion provided with an outside thread. Wherein: each of the screw head and the distal portion includes at least one groove, firstly extending over the entire axial length of its thread, and secondly being formed through each thread in such a manner to form tapping means; and the terminal zone of the distal portion is provided with preparation means for preparing a housing in the bone fragments for receiving the intermediate and distal portions of the screw.