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Updated: May 24, 2026
Induction of Adhesion-dependent Signals Using Low-intensity Ultrasound
Published on: May 8, 2012
Effects of different therapeutic ultrasound intensities on fracture healing in rats
Chak-Hei Fung1, Wing-Hoi Cheung, Neill M Pounder
1Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
Abstract:
Low-intensity pulsed ultrasound (LIPUS) with I(SATA)= 30 mW/cm(2) has been proven in facilitating fracture healing, which the spatial average intensity over the on period (I(SATP)) equals 150 mW/cm(2). As active ultrasound wave is only delivered during the on period, we postulate 150 mW/cm(2) is responsible for the beneficial effect of LIPUS. In this study, we compare the biologic effects of 30 mW/cm(2) and 150 mW/cm(2). We propose I(SATA) = 150 mW/cm(2) could further enhance fracture healing process. Closed femoral fractured Sprague-Dawley rats were randomized into control, LIPUS-30 (30 mW/cm(2)) and LIPUS-150 (150 mW/cm(2)) groups. Weekly radiographs and endpoint microCT, histomorphometry, and biomechanical tests were performed. The results show that LIPUS-30 had significantly higher low-density bone volume fraction and woven bone percentage than that of control and LIPUS-150 in microCT and histologic measurements, respectively. Mechanically, failure torque of LIPUS-30 was significantly higher than control and LIPUS-150 at week 6. In conclusion, LIPUS at I(SATA)= 150 mW/cm(2) did not further enhance fracture healing.
Insights
Low-intensity pulsed ultrasound (LIPUS) at 30 mW/cm² enhanced fracture healing more than 150 mW/cm². The higher intensity did not improve bone repair in rats.
Area of Science:
- Biomedical Engineering
- Regenerative Medicine
- Orthopedics
Background:
- Low-intensity pulsed ultrasound (LIPUS) accelerates fracture healing.
- The effective intensity responsible for LIPUS benefits is debated.
- Spatial Average Temporal Average (I(SATA)) and Spatial Average Temporal Peak (I(SATP)) intensities are key parameters.
Purpose of the Study:
- To compare the effects of two LIPUS intensities on fracture healing.
- To investigate if a higher intensity (150 mW/cm²) enhances healing compared to a standard intensity (30 mW/cm²).
Main Methods:
- Closed femoral fractures were created in Sprague-Dawley rats.
- Rats were randomized into control, LIPUS-30 (30 mW/cm² I(SATA)), and LIPUS-150 (150 mW/cm² I(SATA)) groups.
- Radiographs, microCT, histomorphometry, and biomechanical tests were used for assessment.
Main Results:
- LIPUS-30 group showed significantly higher low-density bone volume fraction and woven bone percentage compared to control and LIPUS-150 groups.
- Biomechanical testing revealed significantly higher failure torque in the LIPUS-30 group than control and LIPUS-150 groups at 6 weeks.
Conclusions:
- LIPUS at 150 mW/cm² I(SATA) did not further enhance fracture healing in rats.
- The standard intensity of 30 mW/cm² I(SATA) demonstrated superior bone healing outcomes.
- Findings suggest that higher LIPUS intensity may not be beneficial for fracture repair.
