Abstract: The invention relates to a surgical tool (10) for reaming the diaphyseal canal of long bones, in particular of the femur, humerus, or tibia, in order to insert an intramedullary rod. The modular reaming head includes: a central core (60) and a peripheral bushing (24) that is coaxial to said central core (60) and connected via a plurality of vanes (41a-41e) connecting a front surface (12) of the tool (10) to a rear surface (11) of the tool (10), and teeth (26a-26e) on the outer surface of said peripheral bushing (24). The openings allow material to pass toward the rear when the tool advances within the diaphyseal canal, minimizing pressure and friction, resulting in a positive effect on the rate of clinical complications. The tool is preferably made using the metal injection molding (MIM) technique in order to reduce production costs and enable the one-time use thereof. The reaming head of the invention can be perfectly combined with composite or metal drive shafts.