A targeting device for guiding a drill arrangement for forming an arc-shaped bore in an assembly of adjacent bones or bone fragments, comprises a support frame, a pivoting device mounted to the support frame and arranged to receive the drill arrangement and to allow a pivoting movement of the drill arrangement along an arc-shaped path having a predetermined radius of curvature rc around a pivot axis. The support frame is provided with at least three fixation devices each configured to fix a bone or bone fragment of the bone assembly to define a fixed position in space of the bone assembly with respect to the pivoting device when the bone assembly is installed on the support frame.