Abstract: The invention concerns an interconnecting device able to lock two spinal osteosynthesis fasteners comprising an osseous fixation section formed by a screw, a bent-back plate or similar device and a body for fixing an integralization rod formed by a diapason head receiving both said rod and a locking screw, said interconnecting device being constituted by two annular elements able to be each externally attached onto one of the diapason heads, each annular element comprising an external locking rod able to slide into the clamping collar, the two clamping collars of the device being screwed down by a common screw traversing said collars.