[Effect of extracorporeal shockwave administration on biological behavior of bone cells in vitro].

Aim: Osteo-destructive effects as well as stimulation of bone growth are often described after extracorporeal shock-wave application (ESWA). A correlation between the applicated energy and outcome is assumed. The purpose of this study was to analyze, whether ESWA has an influence on growth and proliferation of bone cells in vitro.

Methods: Human cancellous bone was cultivated until a confluent cell layer had grown. 5 x 10(5) bone cells were transferred into U-formed tubes, centrifuged and covered with cultivation medium. Thereafter ESWA was applicated in a standardized manner. Number and intensity of ESWA were systematically combined (500, 1000, 2000 and 0.15, 0.26, 0.51 mJ/mm2 energy flux density--EFD, respectively). Ten samples per combination were analyzed. In addition, we examined an untreated control group. Survival, metabolism (alkaline phosphatase activity), type I collagene-synthesis as well as proliferation were determined.

Results: There is a decrease of survival after ESWA depending on the number of impulses and intensity (dose-dependent survival). Cell survival was significantly reduced to 40% after 2000 impulses with high energy rates. Metabolism of surviving cells is not altered by ESWA in comparison with controls. Depending on the number but not on the energy of impulses the type I collagene-synthesis of surviving cells decreased. Between the 3rd and the 8th day after ESWA proliferation increased significantly in cell cultures treated with 2000 impulses of medium or high energy rates.

Conclusions: There is a direct relation between dose and effect for ESWA: A minimum number of impulses and EFD is needed to cause effects on bone-cells. This mainly depends on the numbers of impulses. Destruction of cells is a short-time effect of high shock-wave-doses, a medium-term effect is a cell-stimulation.