title: Fracture healing enhancement with low intensity pulsed ultrasound at a critical application angle.
abstract: Low-intensity pulsed ultrasound (LIPUS) was shown to have dose-dependent enhancement effect on the osteogenic activity of human periosteal cells that played an important role in fracture healing. It was hypothesized that the stimulatory effects of LIPUS on the periosteal cells could be optimized by adjusting the ultrasound delivered at its critical angle to the surface of bone. This increased the transmission of ultrasound waves on periosteum. By using a rat femoral fracture model, the stimulatory effects of LIPUS transmitted at 0°, 22°, 35° and 48°, and the sham-treatment control were investigated. Treatment efficacy was assessed using radiography, micro-computed tomography (micro-CT), histomorphometry and torsional test. The results showed that callus mineralization and bridging, biomechanical properties were significantly enhanced in the 35° group over the control and 0° groups after week 8. LIPUS transmitted at 35°, which could be the critical application angle, showed the best enhancement effects among all the other groups. LIPUS transmitted at a critical application angle may have greater enhancement effects in fracture healing.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China.
authors.forename: Shu Lu
authors.initials: SL
authors.lastname: Chung
authors.forename: Neill M
authors.initials: NM
authors.lastname: Pounder
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: de Ana
authors.forename: Ling
authors.initials: L
authors.lastname: Qin
authors.forename: Kwok
authors.initials: K
authors.lastname: Sui Leung
authors.forename: Wing Hoi
authors.initials: WH
authors.lastname: Cheung
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D017102:Fracture Healing / Q000502:physiology*; D021621:Imaging, Three-Dimensional; D010012:Osteogenesis; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D018709:Statistics, Nonparametric; D019415:Torque; D014464:Ultrasonic Therapy / Q000379:methods*; D055114:X-Ray Microtomography