A fixation element configured to affix a blocking plate to a fixation plate of an intervertebral implant, the fixation element comprising:the fixation element including:a shaft having a distal end and a proximal end, the shaft defining external threads between the distal end and the proximal end； anda head extending from the proximal end of the shaft, the head defining external threads that are configured to be engaged by a driver assembly,wherein the threads of the head and the threads of the shaft have substantially similar pitches.
