title: Effect of trabecular orientation on mechanical resistance and ultrasound propagation in specimens of equine vertebrae.
abstract: Osteoporosis involves alterations, not only in density, but also in the architectural organisation of the bone; in particular, trabecular orientation, following the skeletal load directions, lends a high degree of stiffness to the whole bone. We investigated the relationship between trabecular orientation, density, stiffness and ultrasound (US) propagation in two orthogonal directions (par. = parallel to, and ort. = orthogonal to the main orientation of the trabeculae) in cylindrical equine bone specimens (thoracic vertebrae) where a preferential orientation is present. A total of 15 cylinders were progressively decalcified with 0.2 mol/L ethylenediaminetetraacetic acid (EDTA). At different levels of decalcification, we measured the apparent density (g/cm(3)), bone mineral density or BMD (g/cm(2)), stiffness coefficient (MPa) and various US parameters. Before decalcification, stiffness values were the same in all directions. As the decalcification proceeded, the stiffness declined and, at low BMD values, it was significantly different in the two directions, being the highest in the par. one. Different behaviours of US parameters were observed in the two directions: SoS (speed of sound) was closely related to apparent density, BMD and stiffness in the par. direction (r = 0.88, 0.92 and 0.88, respectively, p < 0.0001). In the ort. direction, no significant association has been found between SoS and apparent density, BMD or stiffness. In the same experimental setup, US fast wave amplitude (FWA) was related to apparent density and BMD in the par. direction (r = 0.72 and 0.67, respectively, p < 0.0001) and in the ort. direction (r = 0.83 and r = 0.84 respectively, p < 0.0001). FWA was also correlated to stiffness in both directions (r = 0.61 par.; 0.81 ort., p < 0.0001). These results show that trabecular orientation strongly influences both mechanical properties of bone and US propagation. Furthermore, we found that US parameters can be predictors of mechanical properties of the bone independent of bone density.
authors.affiliation: Department of Anatomy and Histology, University of Modena and Reggio Emilia, Modena, Italy. fcavani@unimore.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Cavani
authors.forename: Milena
authors.initials: M
authors.lastname: Fini
authors.forename: Francesca
authors.initials: F
authors.lastname: de Terlizzi
authors.forename: Matteo
authors.initials: M
authors.lastname: Cadossi
authors.forename: Luca
authors.initials: L
authors.lastname: Ciminelli
authors.forename: Sergio
authors.initials: S
authors.lastname: Ortolani
authors.forename: Roberto
authors.initials: R
authors.lastname: Cherubini
authors.forename: Domenico
authors.initials: D
authors.lastname: De Aloysio
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giavaresi
authors.forename: Ruggero
authors.initials: R
authors.lastname: Cadossi
authors.forename: Valerio
authors.initials: V
authors.lastname: Canè
mesh_terms: D015502:Absorptiometry, Photon; D000818:Animals; D001696:Biomechanical Phenomena; D015519:Bone Density; D003648:Decalcification Technique; D006736:Horses / Q000033:anatomy & histology*; D023421:Models, Animal; D010024:Osteoporosis / Q000000981:diagnostic imaging*; D013131:Spine / Q000000981:diagnostic imaging*; D014463:Ultrasonography