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Monitoring the degradation of bone elastic properties induced by microgravity: a proposal.
No full textBackground
Important alterations occurring in living organisms during space flight concern the trabecular compartment of load-bearing bones, and result in significant bone mineral loss and decay of mechanical properties [1, 2].
Composition, mineral content, and the complex micro-scale trabecular microarchitecture contribute together to the macro-scale functional strength of bone as a whole [3]. Bone alterations, including those due to reduced gravitational load conditions, are mainly assessed by measuring bone density, even though, alone, it cannot comprehensively assess skeletal integrity [4]. Micro-tomographic techniques [5], not suitable for monitoring, allow for a pre- and post-mission examination of the trabecular bone component, which undergoes the fastest and most important alterations, placing astronauts at serious risk of fracture upon re-entry [5]. Mesoscale studies in modeled microgravity conditions combined with numerical simulations, show that degradation of apparent mechanical properties must be considered to achieve an accurate description of bone performance [6, 7].
To quantify the pathological alterations in the bone micro-architecture in a clinical setting, a patented, CE marked, software medical device, the Bone Elastic Structure Test, BES TEST, has been developed. Results are uncorrelated to BMD and independent of load [8, 9]. BES TEST has a diagnostic accuracy of 78% as a 3-year fracture risk estimator [10] and can be used to complete the densitometry picture and as monitoring tool for bone follow-up in in rheumatology [9], oncology [11], nephrology [12] and rare bone diseases [13].
Its prospective application for bone alteration monitoring during spaceflights is discussed.
Method
BES TEST simulates the application of forces on an X-ray functional biopsy of the patient’s hand [14-19]. Results are combined in an index, BSI, and its T-score and Z-score (Fig.1). Characteristics: X-ray dose < 0.0005 μSV; CV intra-operator=0.06; 95%CI±8 BSI; CV inter-operator =0.11; 95% CI=±10.8 BSI [20, 21], in line with the diagnostic gold standard.
Requirements for investigation of BES TEST space application:
- Acquisition: x-ray scanner, small detector. Several possible arrangements are possible, tests in simulated space flight will clarify the best configuration.
- Calibration: the acquisition set-up will likely differ from the clinical one.
- Analysis: radiograms upload to automatic service.
Results
BES TEST monitors trabecular bone, which changes more rapidly than cortical bone and BMD in response to physio-pathological alterations, like those occurring during spaceflight.
Conclusion
BESTEST is fast, easy to perform, cost-effective and can be significantly repeated within just weeks, showing potential for monitoring the changes in bone functionality during long-duration space missions.
Acknowledgements
Area Science Park financially supported the development of this work at various stages.
References
1. Vico, L. et al. Bone. 1998.
2. Lang, T. et al. J Bone and Mineral Research. 2004.
3. Kleerekoper, M. et al. Calcif Tissue Int. 1985.
4. J.D. Sibonga et al. Aerosp.Med.Hum. perform. 2015.
5. J.D. Sibonga et al. J. Clin. Densitom. 2020.
6. Cosmi F. et al. J. Mech. Behav. Biomed. Mater. 2009
7. Francesca Cosmi et al. J. Mech. Behav. Biomed. Mater. 2015
8. Cosmi F et al. Mater Today: Proc. 2018.
9. Saviola G. et al. Minerva Medica. 2019.
10. Francesca Cosmi et al. 2023.
11. S. Saracchini et al. 2019.
12. M. Ferraro et al. NDT. 2021.
13. Cosmi F and Maximova N. Mater. Today. 2019
14. Wilczek M. L et al. Eur Radiol. 2013.
15. Albanese CV et al. R. Radiol Med. 2011.
16. Alenfeld FE et al. Osteoporosis Int. 1998.
17. Mele R. Osteoporos Int. 1997.
18. Tonti E. Computer Modeling in Engineering and Science. 2001.
19. Cosmi F. Molecular and Cellular Biology. 2015.
20. Cosmi F. et al. Proc IMechE Part C. 2022.
21. Cosmi F. et al. Proc IMechE Part C. 2023
Editorial
No full textThis volume collects 52 papers, invited after selection among the 90 presentations given at the DAS 2017 - 34th
Danubia Adria Symposium on Advances in Experimental Mechanics, 19 - 22 September 2017, Trieste, Italy,
organized by prof. Francesca Cosmi, Department of Engineering and Architecture at University of Trieste and
M2Test srl, under the patronage of the Danubia-Adria Society on Experimental Methods (DAS) and its Italian
Member Organization, Società Scientifica Italiana di Progettazione Meccanica e Costruzione di Macchine (AIAS).
During the Symposium, the Members of the Scientific Committee of the Danubia-Adria Society on Experimental
Methods (http://das.tuwien.ac.at) ensured a high standard selective evaluation process of the presentations given at
DAS 2017. Each presentation was rated by at least 2 reviewers and, following a final discussion within the DAS
Scientific Committee, the Authors of the top presentations were invited to submit a full paper. Reviewing of
manuscripts submitted for publication started in November 2017, with at least 2 reviewers per paper and further
revision by the DAS 207 Organizing Committee. The entire process was completed by February 2018, and 52 papers
were finally accepted for publication.
The papers included in this volume are representative of the experimental work carried on in several European
and non-European countries: Argentina (1), Austria (7), Croatia (2), Czech Republic (4), Germany (4), Hungary
(10), Italy (6), Japan (1), Poland (6), Romania (3), Serbia (3), Slovakia (4), Slovenia (1). Several areas of
experimental mechanics were covered during the Symposium and are represented here: biomechanics; integration of
mathematical and numerical methods with experimental results; instrumentation; material characterization and
testing; practical applications and case studies; recent developments in international Standardization and technical
regulations and structural analysis.
The variety of validation techniques, reliability assessment experiences and materials analyses addressed in this
volume testifies that, even in an increasingly digitalized and connected world of automation driven by data exchange
in manufacturing technologies, experimental methods are ever more relevant and increasingly important
Come stanno le tue ossa? Nuovi strumenti diagnostici per la salute dell'osso
No full textIntervengono Francesca Cosmi, docente di Progettazione meccanica e Costruzione di macchine dell'Università di Trieste e Alessandra Nicolosi, amministratore delegato M2TES
Implementation of correctness criteria for the bone structure analysis by means of a hand-held x-ray system
Get PDFDensitometry alone has been shown to be inadequate to predict all osteoporotic fractures, since 40-50% occur in people who do not have a low bone density. The BESTEST®, Bone Elastic Structure Test, virtually simulates compressive loads on the trabecular architecture’s reconstructions obtained from digital radiographs of first proximal epiphyses of the non-dominant hand. The radiograms are acquired by a hand-held portable x-ray system equipped with a digital sensor. While in certain cases these systems present risks that are no greater than with standard systems, issues related to: (i) position of the handheld X-ray device relative to the operator, (ii) risk of misalignment of the X-ray units during exposure, (iii) patient protection and (iv) correct positioning of the sensor must still be addressed. A special stand and a customized sensor holder have been therefore designed, so that safety for patient and operator and repeatability of the exam have been improved
A new numerical test for quantifying microgravity-induced bone alterations in cosmonauts
No full textOne 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., “The role of three dimensional trabecular microstructure in the pathogenesis of vertebral compression fractures”, Calcif Tissue Int, Vol. 37, pp. S594-S597, 1985.
2. Vico, L. et al., “Effects of gravitational changes on the bone system in vitro and in vivo”, Bone, Vol. 22, pp. 95-100, 1998.
3. Lang, T. et al., “Cortical and trabecular bone mineral loss from the spine and hip in long duration spaceflight”, 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., “The Application of the Cell Method in a Clinical Assessment of Bone Fracture Risk”, Acta of Bioengineering & Biomechanics, Vol. 9, pp. 35-39, 2007.
6. Cosmi F., Mazzoleni G., “Un nuovo metodo strutturale per la valutazione del rischio di frattura nelle malattie degenerative”, 41° Convegno AIAS, Vicenza (I), Sept. 5-8, 2012
Mechanical characterization of 3D-printed samples
Get PDFAdditive manufacturing is gaining greater and greater popularity in the last few years, with fused deposition modelling (FDM) becoming an accessible tool for rapid prototyping with plastic-based materials. Due to its building process, the mechanical properties of 3D-printed objects are substantially different from those of the same object of the same material, but obtained by a different manufacturing process, i.e. injection molding. In this paper, we investigate the results of tensile tests on 3D-printed specimens made of various plastic and composite materials
Morphological indexes and structural parameters in trabecular bone micro-models
No full textIt is well known that the mechanical behaviour of cancellous bone depends not only on its mineral content but also on the trabecular architecture, which appears to be the main responsible for trabecular bone anisotropy. In literature, the fourth order tensors that describe the elastic properties of the material (very demanding from the computational point of view) have been related to the anisotropy MIL second order fabric tensors (easily obtainable) [1-6]. Unfortunately, the formulations developed so far between volume fraction, fabric and elastic properties are bone specific and the coefficients found for one bone are not directly applicable to other bones. This is not unexpected since the normalized MIL eigenvalues Hi show a poor correlation to the stiffness components, as shown for example in Figure 1 (a), where healthy bone structures from different species are considered. However, if the normalized values of stiffness Ei are used instead of the apparent elastic moduli E_sim, correlation increases dramatically even for very different bones, like pig and rat in this case, Figure 1 (b).
Starting from these considerations [6], a new approach resulted in a simple general relationship, linking volume fraction and MIL fabric tensor to the trabecular structure stiffness components. The results presented here show that the model can predict approximately 99% of the variation of the numerically computed elastic moduli for the same, healthy, pooled data set (Figure 2) and can be employed also to assess tissue degeneration due to osteoporosis or microgravity (Figure 3).
Figure 1: Pooled data set from different healthy bone structures (pig and rat) - (a) Computed elastic moduli (MPa) vs. MIL normalized eigenvalues - (b) Normalized elastic moduli vs. MIL normalized eigenvalues
Figure 2: Pooled data set from healthy bone structures - Predicted vs. computed elastic moduli (MPa)
Figure 3: Degenerated bone structures - Predicted vs. computed elastic moduli (MPa)
[1] Cowin S.C., "The relationship between the elasticity tensor and the fabric tensor", Mech. Mat., 1985, 4, 137–147.
[2] Van Rietbergen B. et al., "Relationships between bone morphology and bone elastic properties can be accurately quantified using high-resolution computer reconstructions", J. Orth. Res., 1998, 16, 23–28.
[3] Kabel J. et al, "Constitutive relationships of fabric, density, and elastic properties in cancellous bone architecture", Bone, 1999, 25, 481–486.
[4] Homminga J. et al, "The dependence of the elastic properties of osteoporotic cancellous bone on volume fraction and fabric", J. Biomech., 2003, 36, 1461–1467.
[5] Zysset P.K., "A review of morphology–elasticity relationships in human trabecular bone: theories and experiments", J. Biomech., 2003, 36, 1469–1485.
[6] Van Ruijven L.J. et al, "Prediction of mechanical properties of the cancellous bone of the mandibular condyle", J. Dent. Res., 2003, 82(10), 819–823.
[7] Cosmi F., "Morphology-based prediction of elastic properties of trabecular bone samples", Acta Bioeng. Biomech., 11(1), 2009, 3-
Numerical evaluation of trabecular bone alterations: A cell method application
Get PDFBone tissue is a complex multi-scale material and its morphological and functional characteristics are influenced during one’s life by constant changes, physiological and pathological. A recent technique can classify the mechanical response of trabecular bone by simulating the application of loads with a Cell Method model derived from plane radiographic images of the proximal epiphyses in the patient’s hand fingers, thus complementing the individual assessment with a low cost exam. The mesoscale pathological modifications (i.e. due to osteoporosis) can be detected and quantified, despite the simplification due to the use of radiograms. In this work, this approach is validated using four idealized structures, modelling different trabecular organizations in the site of interest. Then, the results obtained in six female subjects, age between 35 and 77, are discussed to highlight the potential relevance of this application for the study, in quantitative terms, of the trabecular bone alteration due to age, pathological conditions and lack of exposure to physiological mechanical stimuli (micro-gravity conditions)
A micro-mechanical model of the elastic properties of a short fibre reinforced polyamide
No full textThe elastic moduli of short fibre polyamide reinforced with different contents of glass fibres were computed by means of a numerical model. The analyses were based on the reconstructions of the internal fibre structure obtained by micro tomography using synchrotron light. The reconstructed volumes were used in a Cell Method micro-mechanical model in order to simulate the local tensile behaviour of the specimen
Numerical modeling of porous materials’ mechanical behaviorwith the cell method
No full textCell method is a numerical method that has recently been developed. It allows a direct discrete formulation of physical
laws, and therefore it is particularly suitable when heterogeneities are present, as in porous materials. The proposed model
consists of a matrix of constituent cells with randomly distributed voids. Results of simulations in both elastic and plastic
field show a good agreement with experimental data for sintered alloy
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