Disclosed herein is an apparatus for forming a hole in a spongelike bone. The apparatus includes a catheter tube, an expansible structure coupled to a front end of the catheter tube, a hub having a fitting coupled to a rear end of the catheter tube, and a probe. The catheter tube includes the probe and one lumen surrounding the probe, both of which are disposed inside the catheter tube. The probe is fixed to the hub or a rear cap of the hub at a rear end thereof and comes into contact with an inner front end of the expansible structure at a front end thereof.
