title: In vivo microMRI-based finite element and morphological analyses of tibial trabecular bone in eugonadal and hypogonadal men before and after testosterone treatment.
abstract: Osteoporosis is a major public health problem in men. Hypogonadal men have decreased BMD and deteriorated trabecular bone architecture compared with eugonadal men. Testosterone treatment improves their BMD and trabecular structure. We tested the hypothesis that testosterone replacement in hypogonadal men would also improve their bone's mechanical properties. Ten untreated severely hypogonadal and 10 eugonadal men were selected. The hypogonadal men were treated with a testosterone gel for 24 mo to maintain their serum testosterone concentrations within the normal range. Each subject was assessed before and after 6, 12, and 24 mo of testosterone treatment by microMRI of the distal tibia. A subvolume of each microMR image was converted to a microfinite element (microFE) model, and six analyses were performed, representing three compression and three shear tests. The anisotropic stiffness tensor was calculated, from which the orthotropic elastic material constants were derived. Changes in microarchitecture were also quantified using newly developed individual trabeculae segmentation (ITS)-based and standard morphological analyses. The accuracy of these techniques was examined with simulated microMR images. Significant differences in four estimated anisotropic elastic material constants and most morphological parameters were detected between the eugonadal and hypogonadal men. No significant change in estimated elastic moduli and morphological parameters was detected in the eugonadal group over 24 mo. After 24 mo of treatment, significant increases in estimated elastic moduli E(22) (9.0%), E(33) (5.1%), G(23) (7.2%), and G(12) (9.4%) of hypogonadal men were detected. These increases were accompanied by significant increases in trabecular plate thickness. These results suggest that 24 mo of testosterone treatment of hypogonadal men improves estimated elastic moduli of tibial trabecular bone by increased trabecular plate thickness.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, New York 10027, USA.
authors.forename: X Henry
authors.initials: XH
authors.lastname: Zhang
authors.forename: X Sherry
authors.initials: XS
authors.lastname: Liu
authors.forename: Branimir
authors.initials: B
authors.lastname: Vasilic
authors.forename: Felix W
authors.initials: FW
authors.lastname: Wehrli
authors.forename: Maria
authors.initials: M
authors.lastname: Benito
authors.forename: Chamith S
authors.initials: CS
authors.lastname: Rajapakse
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Snyder
authors.forename: X Edward
authors.initials: XE
authors.lastname: Guo
mesh_terms: D016880:Anisotropy; D004548:Elasticity; D020342:Finite Element Analysis; D006801:Humans; D007006:Hypogonadism / Q000188:drug therapy* / Q000503:physiopathology; D008279:Magnetic Resonance Imaging; D008297:Male; D013739:Testosterone / Q000627:therapeutic use*; D013977:Tibia / Q000473:pathology* / Q000503:physiopathology; D013997:Time Factors
chemical_list: D013739:Testosterone