Experimental assessment of calvarial bone defect re-ossification stimulation using low-intensity pulsed ultrasound

Ultrasound treatment has been proposed by several authors to enhance the repair of long bone injury. The present study investigated in a murine model the treatment by low-intensity pulsed ultrasound (LIPUS) of calvarial flat bone defect. The animals were operated to create bone defect and exposed to ultrasound for 5 min per day, 5 d per week, during two weeks. Two intensities of ultrasound (1 MHz, 100 Hz pulse repetition frequency and 20% duty cycle) were investigated: 100 and 300 mW/cm(2) spatial-averaged, time-averaged. Re-ossification surface and volume were determined after 30 and 60 days using computerized X-ray tomography in all animals of the control and treated groups. The results showed a significant increase of bone re-ossification in the group treated with the higher-intensity ultrasound (mean value of 18% volume reconstruction), whereas lower bone reconstruction was observed in the lower-intensity and control groups (respective mean values of 10 and 12% volume reconstruction).