Pressure-time profiles of a focused and a radial shockwave device: Measurements in tissue, ex vivo, and in a water bath.

Abstract

In the past we have employed shock waves (SW) to stimulate periosteal cell proliferation in both rat and rabbit models. In order to understand the mechanical insult to the cells, single pulse pressure-time profiles were recorded at a periosteal surface using a needle hydrophone for both a ballistic and an electrohydraulic SW source. Three sets of measurements were taken: free field (FF) in a water bath, intramuscularly (IM) by inserting the needle into the leg of a sacrificed rabbit and placing it near the tibial bone corner, and ex vivo using an extracted rabbit tibia bone in a water bath and placing the needle closer to the bone surface. For the ballistic source, the IM and FF measurements of the leading positive peak matched, whereas for the electrohydraulic source, it was attenuated by 57%. The compression was followed by a tensile wave, and for both sources, IM and FF measurements of the pressure and duration were similar. The ex vivo measurements showed additional secondary peaks for the measurements at the bone surface, attributable to surface reflections or creeping waves. These data suggest that periosteal cells subject to SWs are exposed to complex pressure fields that likely stimulate the cell proliferation.