[Study of the effects of intermittent low-intensity pulsed ultrasound on callus formation of tibia in rabbit [a radiological and biomechanical evaluation]]

Application of low intensity ultrasound has been used for treatment of many diseases in medicine and has suggested for accelerating wound healing process, modifying scar tissue and relief of pain. The aim of this study was radiological and biomechanical evaluation of low-intensity pulsed ultrasound on callus formation of tibia in rabbit. In this experimental study 20 male white Dutch rabbits [weighting 2.5-3kg] aged about 6 months were used. Under general anesthesia and sterile condition a standardized mild-tibial osteotomy was performed in the right tibia and bilateral external fixator was applied to the lateral aspect. The rabbits were randomly divided into control and ultrasound groups. After three days of surgery the rabbits of ultrasound group received ultrasound with 1MHz and pulsed 1:1 and 50 and 100 mw/cm[2] for 15 min/day and the control groups did not received any treatment. The rabbits were killed at week 7 post surgery by inhalation of chloroform. Radiographs were taken following killing the animals immediately. Biomechanical test of rabbits tibiae were used and the samples were taken from the callus of fracture. Radiological scoring of tibia according to density of mineralized callus in the control group was 3.5 +/- 0.35 and in the ultrasound group [50mw/cm[2]] was 2.55 +/- 0.25 and in the ultrasound group [100mw/cm[2]] was 3.25 +/- 0.38. Thus there was it has no differences between ultrasound and control group in radiographs. Force maximum in the biomechanical test of the tibia in the control group was 65.75 +/- 6.16 and in the ultrasound group [50mw/cm[2]] was 49.42 +/- 5.27 and in the ultrasound group [100mw/cm[2]] was 79.12 +/- 9.63, the differences were not significant. These finding suggest that programmed ultrasound therapy has no effect on facture repair and callus formation of rabbits tibiae