Abstract: A screw fastener system includes a plate having formed therein, centered on an axis perpendicular to the plane of the plate: a circularly generally cylindrical orifice of depth h and of cross-section equal to D, an orifice of cross-section equal to d less than D, and a housing, the orifices being situated on either side of the housing, the height of the housing being equal to H and its width having a value L not less than D, and a fastener screw constituted by a shank carrying a thread, the section S of the shank being no greater than the value d, and a head arranged for screwing into the cylindrical orifice, the height E of the head being no greater than the height H of the housing. The system is applicable to fastening implants such as spinal or other osteosynthesis plates.