A series of surgical tools (11, 21, 31, 41, 51, 61, 71, 81) have respective operative heads (16, 26, 36, 46, 56, 66, 76, 86&96) mounted adjacent a distal end of an elongate
waveguide (12, 13, 14). The operative heads (16, 26, 36, 46, 56, 66, 76, 86&96) are used to remove PMMA
bone cement (2, 5) from within a hollow bone (1), such as a
femur (1), as part of a
prosthesis revision operation, such as replacement of an artificial hip joint. Torsional-mode ultrasonic vibrations are transmitted along the
waveguide (12, 13, 14) to the respective operative heads (16, 26, 36, 46, 56, 66, 76, 86&96), which are applied to the
bone cement (2, 5),
softening it and facilitating its removal. Elongate radial channels (18, 23, 28, 38) extend across
cement-contacting faces of several of the surgical tools (11, 21, 31, 41, 71, 81), acting to focus and transmit the torsional-mode ultrasonic vibrations into adjacent
cement (2, 5). In another tool (51), scalloped recesses (58, 59) in its
cement-contact face have substantially the same effect, while in a further tool (61), a series of notches (65) along a distal edge (69) of the tool (61) have an analogous function. The operative heads (76, 86, 96) of certain tools (71, 81) can be embedded into a cement plug (5) then used to pull the plug (5) as a unit out of the bone (1).