title: Effects of risedronate on trabecular microstructure and biomechanical properties in ovariectomized rat tibia.
abstract: We determined the effect of risedronate on the trabecular microstructure of ovariectomized rat tibiae, using micro-computed tomography, in order to investigate how changes in microstructure contribute to biomechanical properties. Fifty 18-week-old rats underwent sham operation (n=10) or ovariectomy (OVX) (n=40). The OVX rats were further divided into four groups (n=10 for each group) and treated with risedronate at doses of 0, 0.1, 0.5 or 2.5 mg/kg for 9 months. OVX caused deterioration of three-dimensional trabecular microstructure, notably structure model index (SMI) and connectivity density, while treatment of OVX rats with risedronate at 0.5 and 2.5 mg/kg improved those deleterious microstructural changes. Biomechanical property, as assessed by finite element analysis (FEA), correlated significantly with trabecular bone volume fraction (BV/TV), and the correlation further increased substantially when microstructural parameters were added, especially SMI and connectivity density, with risedronate therapy. Thus, it is suggested that, in addition to increasing bone mass, risedronate improves biomechanical property by maintaining a plate-like structure as well as connectivity of trabeculae.
authors.affiliation: Department of Radiology, Nagasaki University School of Medicine, 1-7-1 Sakamoto, 852-8501 Nagasaki, Japan. masako@net.nagasaki-u.ac.jp
authors.forename: Masako
authors.initials: M
authors.lastname: Ito
authors.forename: Akifumi
authors.initials: A
authors.lastname: Nishida
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Aoyagi
authors.forename: Masataka
authors.initials: M
authors.lastname: Uetani
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Hayashi
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kawase
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D012968:Etidronic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D020342:Finite Element Analysis; D021621:Imaging, Three-Dimensional / Q000379:methods; D010052:Ovariectomy; D051381:Rats; D017207:Rats, Sprague-Dawley; D000068296:Risedronic Acid; D013977:Tibia / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000503:physiopathology; D014057:Tomography, X-Ray Computed
chemical_list: D050071:Bone Density Conservation Agents; D000068296:Risedronic Acid; D012968:Etidronic Acid