title: Ultrasound and fragility fracture: is there a role?
abstract: Osteoporotic fracture is known to have impaired healing capacity and therefore takes longer time to heal, as compared with younger one. The mechanism of impaired osteoporotic fracture healing is multifactorial, where lower responsiveness to mechanical loading is generally believed to be one factor, yet not absolutely confirmed. In recent years, low intensity pulsed ultrasound (LIPUS) is demonstrated to have good efficacy in treating normal fracture healing, as proven by many randomized controlled trials, as well as in vitro and animal evidences. The effects of LIPUS on osteoporotic fracture healing was also validated in an animal study, which revealed that osteoporotic fractured bone of SD rats showed radiologically and biomechanically comparable responses to LIPUS as age-matched normal fracture healing, in terms of callus width, bridging rate, bone volume fraction, and stiffness etc. Gene expression profiling also confirmed that osteoporotic fractured bone responded to LIPUS very well by upregulating Col1 and BMP2 (osteogenesis) at early phase, VEGF (angiogenesis) at middle phase and RANKL (remodeling) at late phase. These confirm that osteoporotic bones respond well to LIPUS as good as normal bone. These findings may be associated with estrogen receptors (ERs), as estrogen depletion is sensed and relayed by ERs and ERs also function as mechano-sensors. A previous study observed a delayed ERs expression pattern in fracture callus of OVX rats, as compared with SHAM rats, which correlated well with the expression pattern of BMP-2 (callus formation-related gene). Hence, the responses of osteoporotic fractured bone to LIPUS may be related to the local ERs expression at fracture callus that needs further experiments to validate.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong; Orthopaedic Research Laboratory of Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China. Electronic address: louis@ort.cuhk.edu.hk.
authors.forename: Wing-Hoi
authors.initials: WH
authors.lastname: Cheung
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong; Orthopaedic Research Laboratory of Translational Medicine Research and Development Center, Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, China.
authors.forename: Kwok-Sui
authors.initials: KS
authors.lastname: Leung
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong.
authors.forename: Simon Kwoon-Ho
authors.initials: SK
authors.lastname: Chow
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D002146:Bony Callus / Q000098:blood supply / Q000473:pathology*; D004195:Disease Models, Animal; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000378:metabolism; D017102:Fracture Healing; D005786:Gene Expression Regulation; D006801:Humans; D010012:Osteogenesis / Q000502:physiology; D058866:Osteoporotic Fractures / Q000000981:diagnostic imaging / Q000473:pathology*; D010052:Ovariectomy; D053245:RANK Ligand / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014463:Ultrasonography
chemical_list: D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D053245:RANK Ligand
keywords: LIPUS; estrogen receptor; fracture healing; low intensity pulsed ultrasound; osteoporosis