The invention relates to a device (1) for the amelioration of a recess (8) e.g. a recess in a (human) bone (7). The device comprises an element (2) for producing or coupling mechanical energy, and a cylindrical collar (4) comprising a cylindrical lateral surface having an outside diameter and having a central recess (26) for accommodating a guide pin (3). The guide pin (3) is provided to be inserted substantially down to the base of the recess (8) before applying oscillations, and in the region of the end thereat facing the base of the recess it is surrounded by an amelioration sleeve (6) made from a material that can be liquefied by way of ultrasonic oscillations. The cylindrical lateral surface of the amelioration sleeve (6) substantially has the same outside diameter as the collar (4), and the guide pin (3) is accommodated in the central recess (26) in a displaceable manner such that the collar (4) upon applying ultrasonic oscillations can be displaced relative to the guide pin (3) in the direction toward the base of the recess (8) while liquefying and laterally and/or longitudinally displacing the material of the amelioration sleeve (6).
