An apparatus to aid removal of a prosthetic implant cemented into bone that has an adapter to engage a proximal end of the implant, a clamp screw to hold the engaged end to the adapter in good acoustic contact, a generator for torsional or longitudinal mode ultrasonic vibrations and a coupling link to transmit the ultrasonic vibrations to the adapter and thence to the implant, the proximal end of the implant being gripped between a conical tip of the clamp screw and a raised portion of the adapter to avoid damping flexural mode oscillations induced in the implant by making the zone of contact between the adaptor and implant as narrow as possible.