title: Effects of different therapeutic ultrasound intensities on fracture healing in rats.
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.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
authors.forename: Chak-Hei
authors.initials: CH
authors.lastname: Fung
authors.forename: Wing-Hoi
authors.initials: WH
authors.lastname: Cheung
authors.forename: Neill M
authors.initials: NM
authors.lastname: Pounder
authors.forename: F Javier
authors.initials: FJ
authors.lastname: de Ana
authors.forename: Andrew
authors.initials: A
authors.lastname: Harrison
authors.forename: Kwok-Sui
authors.initials: KS
authors.lastname: Leung
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D055119:Elastic Modulus; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000628:therapy*; D017102:Fracture Healing / Q000502:physiology* / Q000528:radiation effects*; D011859:Radiography; D051381:Rats; D013718:Tensile Strength; D016896:Treatment Outcome; D014464:Ultrasonic Therapy / Q000379:methods*