Sapin, Emilie (2008) Subject-specific vertebral bone mechanical properties assessment using low-dose x-ray imaging devices : prediction of fracture risk. PhD thesis Biomécanique, Laboratoire de Biomécanique, ENSAM 2008ENAM0036 p.167.
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Abstract
Given the ageing population, osteoporosis and vertebral fractures are considered as a major public health issue. Vertebral fractures firstly arise without pain, so that two thirds of them commonly escape clinical diagnosis. The cost of preventive treatment is very high and need to identify patients with high risk. Hence, the key issue is to improve the prediction of the vertebral fractures. A low bone mineral density (BMD) assessed by DXA does not always explain prevalent fractures, suggesting that other parameters have to be taken in account. Mechanical approaches based on finite-element models have been proposed to predict strength of osteoporotic vertebrae. However, these models are based on quantitative computed tomography and cannot be used to analyse the whole spine in vivo for patients’ follow-up because of the high radiation dose. Thus, the present study proposes subject-specific finite element models based on a low-dose imaging system. They compute a value of the failure load close to the real one (FMEF = 0,94 Fexp +242,6 ; r² = 0,83, IC95% = ± 674 N) with a low numeric cost (about ten minutes), thanks to the assessment of the specific 3D geometry and the specific individual vertebral bone mechanical properties. Indeed, relationships have been proposed in a first experiment, made on 19 vertebrae, to predict the spongious bone mechanical properties from the BMD assessed using the low-dose EOS® device. Moreover, given the lack of information concerning the macro-scale vertebral cortical bone mechanical properties, an original experiment has been carried out to compute the Young’s modulus of a cortico-spongious region using an inverse finite-element method. Finally, mechanical tests were made on 15 vertebrae to assess failure loads in order to evaluate the prediction of the model. This work underlines the potential of low-dose X-ray devices to make subject-specific finite-element models that could be clinically used to predict vertebral fracture risk
| Item Type: | PhD Thesis (PhD) |
|---|---|
| PhD Supervisor: | Mitton, David |
| Date: | 26 November 2008 |
| Board of examiners: | Benhamou, Claude-Laurent and Bouxsein, Mary and Cortet, Bernard and Pioletti, Dominique and Mitton, David and Skalli, Wafa and Bousson, Valérie and Féron, Jean-Marc |
| Ecole Doctorale: | ED 432 ECOLE DOCTORALE SCIENCES DES METIERS DE L'INGENIEUR |
| Discipline: | Biomécanique |
| Collection (Fonds): | Arts et Métiers ParisTech (ENSAM) |
| Institution: | ENSAM |
| Department: | Laboratoire de Biomécanique |
| Subjects: | 4. Materials Science, Mechanics and Mechanical Engineering |
| Uncontrolled Keywords: | Biomécanique, Ostéoporose, Vertèbre, Risque de fracture, Os spongieux, Os cortical, Modèle en éléments finis personnalisé, Biomechanics, Osteoporosis, Vertebra, Fracture risk, Cancellous bone, Cortical bone, Subject-specific finite element models |
| ID Code: | 4409 |
| Deposited By: | Emilie SAPIN |
| Deposited On: | 18 December 2008 |
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