A new numerical test for quantifying microgravity-induced bone alterations in cosmonauts

One of the most important alterations that occur in man and experimental animals during spaceflight affects the skeletal system (trabecular compartment of load-bearing bones), and results from an important bone loss and mechanical properties decay. The macro-scale mechanical properties of cancellous bone derive from its mass (composition and mineral content) and from its complex micro-scale structure (trabecular micro-architecture arrangement), and it is widely accepted that both these factors contribute to determine the mechanical strength of the whole bone [1]. In space research, bone quality changes due to unloading, are usually assessed by measuring bone density. More rarely, 3D micro-imaging, complemented by morphological indexes, has been used [2,3]. A software that, by means of numerical simulations, evaluates the load bearing capabilities of trabecular bone from planar radiographic images, has recently been developed at the University of Trieste [4]. The technique, already proved to be able to classify the quality of bone for the evaluation of fracture risk in osteoporotic patients [5,6], is here proposed for a more effective monitoring of bone quality changes in long duration spaceflight. References 1. Kleerekoper, M. et al., \u201cThe role of three dimensional trabecular microstructure in the pathogenesis of vertebral compression fractures\u201d, Calcif Tissue Int, Vol. 37, pp. S594-S597, 1985. 2. Vico, L. et al., \u201cEffects of gravitational changes on the bone system in vitro and in vivo\u201d, Bone, Vol. 22, pp. 95-100, 1998. 3. Lang, T. et al., \u201cCortical and trabecular bone mineral loss from the spine and hip in long duration spaceflight\u201d, J Bone and Mineral Research, Vol. 19, pp. 1006-1012, 2004. 4. Patent: USA No. 10509512, deposited by University of Trieste, 2008. 5. Cosmi F., Dreossi D., \u201cThe Application of the Cell Method in a Clinical Assessment of Bone Fracture Risk\u201d, Acta of Bioengineering & Biomechanics, Vol. 9, pp. 35-39, 2007. 6. Cosmi F., Mazzoleni G., \u201cUn nuovo metodo strutturale per la valutazione del rischio di frattura nelle malattie degenerative\u201d, 41\ub0 Convegno AIAS, Vicenza (I), Sept. 5-8, 2012