Investigation of perfusion in osseous vessels in close vicinity to piezo-electric bone cutting.

Cutting bones by piezosurgery leads to failure of perfusion at the site of the osteotomy, the cause of which cannot be identified immediately. Among other things the formation of vascular thrombi by the transmission of oscillations from the piezoelectric unit to the bone may be responsible. We used three output levels of oscillation that were predefined by the system. The outer cortical bone of the calvaria of rats (n=24) was removed horizontally and the intraosseous vessels exposed at the surface of the osteotomy. The blood flow was then examined repeatedly using intravital fluorescence microscopy. To calculate the transmission of oscillations to the bone, the spatial oscillation frequency of each calvarium and the contact pressure during removal of bone in vitro (n=18) were also examined. After removal of the bone there was constant blood flow at all three levels of oscillation output. In no case did an individual vessel seem to be occluded. The excitation oscillation of the bone was established at 2000 Hz in all spatial directions, irrespective of the predefined oscillation output. The application of piezosurgery does not cause the formation of vascular thrombi in the bone. This probably results from the oscillation damping properties of bone.