Abstract: The apparatus comprises a piezoelectric vibrator adapted to generate ultrasonic energy which is transmitted through an output section 1 to a plastics head 6. The shape of the head 6 may be varied to suit whichever part of a body on which it is to be used. The material and shape of the head 6 is chosen to allow accurate control of frequency and amplitude of the ultrasonic energy. The preferred ultrasonic frequency is in the range of 20-120 kHz.

Abstract: A relatively massive annular body is driven in radial-mode resonant oscillation by an ultrasonic driver that is fixed to the periphery of the annular body, with the axis of its ultrasonic drive oriented for intersection with the central axis of the annular body. A selected chucking device within the bore of the annular body is adapted to engage part of a prosthetic device, to which the resonant oscillation is imparted, for melting bone cement and for severing bony ingrowth into the prosthetic, thus permitting immediate retraction of the prosthetic from its pre-existing implantation in a living bone.

Abstract: A tool for use in removing plastics material from a hole comprises a work surface adapted to contact the material. A piezo-electric transducer is operatively connected through a work horn and causes the work surface to vibrate ultrasonically and thereby to heat locally the plastics material. A cavity is adapted to receive heated plastics material. The cavity has communication with a working zone adjacent the work surface. The work surface comprises an elongate boring member and rearwardly thereof a substantially annular cutting edge; the working zone communicates with the cavity via apertures disposed between the boring member and the annular cutting edge.