Low-intensity pulsed ultrasound (LIPUS) with an intensity (spatial average temporal average,ISATA) of 30mW/cm2has been widely proved to be effective on impaired bone healing, but showing little effectiveness in the treatment of osteoporosis. We hypothesized that the intensity of LIPUS may be a key factor in explaining this difference, thus two intensity levels, the widely used 30mW/cm2and a higher 150mW/cm2, were used to simultaneously treat osteoporosis and osteoporotic bone defect in ovariectomized (OVX) rats with a 1-mm drill hole on their left femurs.

Results showed that 150mW/cm2LIPUS augmented the healing rate of the drill hole than 30mW/cm2after 3-week LIPUS treatment, although did not further enhance the healing rate after 6-week LIPUS treatment. For ameliorating osteoporosis, 150mW/cm2LIPUS achieved more advantages over 30mW/cm2in improving bone density, microstructure and biomechanics 6 weeks after LIPUS intervention. In conclusion, LIPUS with an intensity of 30mW/cm2was sufficient to facilitate bone defect healing, but a higher intensity can be considered as a rapid trigger for osteoporotic bone repair. In addition, improving the intensity of LIPUS may be a potentially effective consideration for alleviation of osteoporosis. This research helps promote the clinical application of LIPUS in the treatment of osteoporosis and related diseases.

The relevant research was published inUltrasonicsin May, 2021, with the title of "Longitudinal effects of low-intensity pulsed ultrasound on osteoporosis and osteoporotic bone defect in ovariectomized rats". The doctoral student Shuxin Sun is the first author, and Professor Dean Ta is the corresponding author. This work was supported by the National Natural Science Foundation of China, the Program of Shanghai Academic Research Leader, etc.(Shuxin Sun, Liang Tang, Tingting Zhao, Yiting Kang, Lijun Sun, Chengcheng Liu, Ying Li, Feng Xu, Yi-Xian Qin, Dean Ta*. Ultrasonics. 2021 May;113:106360)