The invention relates to an instrument for connecting a correction rod to a bone screw, the instrument having an axial longitudinal direction and comprising an external first housing part, which includes a hollow portion having an internal thread and a portion that is approximately the shape of a half-shell and that forms a first clamp leg. The instrument further includes an external second housing part, which is approximately the shape of a half-shell and forms a second clamp leg that is hinged on the first clamp leg so as to be pivotable about a pivot axis that extends orthogonally to the axial longitudinal direction.