A tool for fixating a suture anchor in a hard tissue opening with the aid of a material having thermoplastic properties and energy transmitted to the suture anchor for in situ liquefaction of at least part of the material having thermoplastic properties, includes a distal face, an axial channel and a substantially tube-shaped interface piece fitting into the axial channel of the tool, wherein the axial channel and a proximal end of the interface piece are equipped with catch elements cooperating for catching the interface piece in the axial channel when the interface piece is moved in a proximal direction in the axial channel.