ABSTRACT
Fracture healing is a biological complex process that is affected by several internal and external factors. One of the external factors is mechanical stimulation by ultrasound waves. There is a controversy about the effects of these waves on bone healing. The aim of this research was to evaluate effects of low-intensity pulsed ultrasonic waves on experimental tibial fracture in New Zealand Rabbit. This is an experimental study in which, 36 male adult New Zealand rabbits were randomly divided into four groups [3 experimental groups and 1 control group]. All of the animals, except the control group, were operated for inducing the experimental fracture on their right tibia. After healing of wounds, the sites of bone fractures in experimental groups were exposed to pulsed ultrasound waves for 2 and 4 weeks. Then all of the animals were killed and right tibias were removed. After fixation and processing of samples, the slides were prepared from paraffin blocks and were stained with H and E. Finally, the slides were studied for stereological analysis of bone healing and the data of each group was analyzed by Mann-Whitney and Kroscal Wallis tests. The Results of this study showed that mean volume changes in cartilaginous callus was significantly higher in ultrasound- exposed rabbits compared to the control group [P<0.05]. No significant differences was seen between experimental and control groups for other parameters such as granulation, mesenchymal tissue and bone tissue. Pulsed-ultrasound waves with frequency about 1 MHz [Mega Hertz] may be useful to increase fracture healing of tibia in rabbit