The present invention discloses a method of using beads to create a cavity in a bone, which includes introducing beads into a bone by applying a pressure on said beads, wherein the beads are metallic beads able to be attracted by a magnet and withdrawing the beads from the bone by magnetic force. Preferably, a pocket is disposed in the bone prior to the introduction of beads, and the introduction and withdraw of the beads are carried out with respect to said pocket.