Instruments for use with a bone anchoring assembly having plug member are disclosed that allow introduction of the plug member and bone cement or other liquid or pasty material into the bone anchor. The bone anchor includes a shaft having a first end and a second end, a channel extending from the first end to the second end, and a plug member which is insertable into the channel and guidable through the channel for closing the channel at the second end. The bone anchor is suitable for minimally invasive surgery in such a way a guide wire can be guided through the bone anchor and after the bone anchor has been anchored in the bone the plug member is inserted to close the open end of the bone anchor.
