Abstract: The apparatus for removal of bone-cement comprises means to generate an ultrasonic signal and a tool element including an elongate stem (1) to transmit the signal to a distal end:. A plurality of spoke members (3), preferably four or eight, extend radially from adjacent the distal end to connect with an annular member (2) surrounding and spaced from the distal end. A plurality of openings (4) are each defined by the stem (1), the annular member (2) and two of the spokes (3). The annular member (2) is provided with a distally facing cutting edge. The spokes (3) are so configured as to transmit to and allow axial movement of the annular member (2) with respect to the stem (1), with an enhanced displacement relative to that of the stem (1).