The invention relates to a bone screw system, an implant system and a method of locking a bone screw system into a bore. The bone screw system comprises a bone screw and a washer. The screw comprises a screw head and a screw shaft. The washer comprises a washer bore. A diameter of the washer bore is larger than an outer diameter of the screw shaft. This allows a displacement of the screw shaft within the washer bore. The diameter of the washer bore is smaller than an outer diameter of the screw head. This prevents the screw head from moving through the washer bore. The screw and the washer comprise each an engagement portion for an engagement with each other. At least one of these engagement portions comprises an inclined surface. The inclined surface is configured to force the screw shaft sideward upon screwing in of the screw so that a longitudinal axis of the screw is tilted relative to the axis of the washer bore.
