[Ultrasonic modelling of bone cement - (reoperation of total hip endoprosthesis) (author's transl)].

In medicine ultrasound is very common in diagnostic and therapeutic applications, in surgery especially as so-called ultrasonic lithotripsy. Up to now experiences in bone surgery are not very successful. Bone cement (PMMA) is a thermoplastic material. Therefore results of ultrasonic lithotripsy cannot be simply transmitted. Investigations show that, because of their thermoplastic quality, the ultrasonic method may be helpful in modelling bone cement, for example in changing endoprosthesis. The preconditions for the use of high frequent oscillating probes are examined experimentally. The necessary visual distinction of bone cement and natural bone may be intensified by fluorochrome labelling of cement.