A device for preparing an opening in hard tissue and/or hard tissue replacement material for implantation of an implant, the device comprising: an oscillation tool adapted to be coupled to an oscillation generator of mechanical oscillations, an augmentation element of a thermoplastic material, and a counter element, • wherein an oscillation tool contact surface (3.3) and a first augmentation element contact surface (4.1) together form a first interface and where a second augmentation element contact surface (4.2) and a counter element contact surface (5.1) together form a second interface, • the device being insertable into an opening (1.1) in hard tissue and/or hard tissue replacement material so that at least one of the first and the second interfaces serves as a liquefaction interface and forms part of a circumferential periphery of the device at least partially surrounded by a circumferential wall of the opening, • material of the augmentation element being, in a vicinity of the liquefaction interface, meltable when pressed against the oscillation tool contact surface (3.3) by the effect of mechanical oscillations coupled into the tool, • wherein the liquefaction interface covers, in a projection along a movement axis, an entire cross section of the augmentation element, • whereby an entire cross section of the augmentation element is meltable by the effect of the mechanical oscillations at the liquefaction interface and displaceable outwardly into and onto structures of the opening, while the liquefaction interface moves with respect to the counter element and/or to the tool and to the body of the remaining augmentation element, and • the augmentation element being meltable by the mechanical oscillations to an extent that the oscillation tool and the counter element may be removed to a proximal side of the opening while augmentation material of the augmentation element remains anchored in the opening, • wherein either the oscillation tool contact surface (3.3) is at a distal end of the augmentation element, and a force for compressing the augmentation element is couplable into the oscillation tool as tensile force, or the oscillation tool contact surface (3.3) is at a proximal end of the augmentation element, a force for compressing the augmentation element is couplable into the oscillation tool as pressing force, and the counter element reaches to the distal side of the augmentation element and has a distal broadening (5.2) with a rearward facing surface forming the counter element contact surface (5.1). • wherein an oscillation tool contact surface (3.3) and a first augmentation element contact surface (4.1) together form a first interface and where a second augmentation element contact surface (4.2) and a counter element contact surface (5.1) together form a second interface, • the device being insertable into an opening (1.1) in hard tissue and/or hard tissue replacement material so that at least one of the first and the second interfaces serves as a liquefaction interface and forms part of a circumferential periphery of the device at least partially surrounded by a circumferential wall of the opening, • material of the augmentation element being, in a vicinity of the liquefaction interface, meltable when pressed against the oscillation tool contact surface (3.3) by the effect of mechanical oscillations coupled into the tool, • wherein the liquefaction interface covers, in a projection along a movement axis, an entire cross section of the augmentation element, • whereby an entire cross section of the augmentation element is meltable by the effect of the mechanical oscillations at the liquefaction interface and displaceable outwardly into and onto structures of the opening, while the liquefaction interface moves with respect to the counter element and/or to the tool and to the body of the remaining augmentation element, and • the augmentation element being meltable by the mechanical oscillations to an extent that the oscillation tool and the counter element may be removed to a proximal side of the opening while augmentation material of the augmentation element remains anchored in the opening, • wherein either the oscillation tool contact surface (3.3) is at a distal end of the augmentation element, and a force for compressing the augmentation element is couplable into the oscillation tool as tensile force, or the oscillation tool contact surface (3.3) is at a proximal end of the augmentation element, a force for compressing the augmentation element is couplable into the oscillation tool as pressing force, and the counter element reaches to the distal side of the augmentation element and has a distal broadening (5.2) with a rearward facing surface forming the counter element contact surface (5.1).