The present application relates to an implant system, preferably for the sacroiliac joint, comprising an implant body with at least two adjacent apertures, at least two screws and an insertion instrument assembly. Each screw comprises a screw head and a threaded elongated shaft. The at least two screws are rotatably engaged within said at least two apertures. The insertion instrument assembly includes a basis, a first holding means and at least one rotatable driving means configured for engagement with a drive of at least one of said at least two screws. The at least two screws or said insertion instrument assembly comprises transmission means such that a rotational movement of a first screw of said at least two screws is transferred to the at least one further screw.