The material mapping strategy influences the accuracy of CT-based finite element models of bones: An evaluation against experimental measurements

Taddei, Fulvia; Schileo, Enrico; Helgason, Benedikt; Cristofolini, Luca; Viceconti, Marco

doi:10.1016/j.medengphy.2006.10.014

Cited by 272 publications

(167 citation statements)

References 32 publications

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“…Each axial slice was filtered using a mean filter of 4x4 pixel size to compensate for the HU overestimation due to this kernel. Bonemat_V3 (Taddei et al, 2007) assigned inhomogeneous isotropic material properties to the elements, based on the HU values of the volume enclosed by each element. HU values were converted to equivalent radiological density (Model 3CT, Mindways Inc.), and the Young's modulus was derived using the relationships proposed by (Schileo et al, 2008).…”

Section: Finite Element Modellingmentioning

confidence: 99%

How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements

Grassi

Väänänen

Ristinmaa

et al. 2016

Journal of Biomechanics

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Subject-specific finite element models have been proposed as a tool to improve fracture risk assessment in individuals. A thorough laboratory validation against experimental data is required before introducing such models in clinical practice. Results from digital image correlation can provide full-field strain distribution over the specimen surface during in vitro test, instead of at a few pre-defined locations as with strain gauges. The aim of this study was to validate finite element models of human femora against experimental data from three cadaver femora, both in terms of femoral strength and of the full-field strain distribution collected with digital image correlation. The results showed a high accuracy between predicted and measured principal strains (R 2 =0.93, RMSE=10%, 1600 validated data points per specimen). Femoral strength was predicted using a rate dependent material model with specific strain limit values for yield and failure. This provided an accurate prediction (<2% error) for two out of three specimens.In the third specimen, an accidental change in the boundary conditions occurred during the experiment, which compromised the femoral strength validation. The achieved strain accuracy was comparable to that obtained in state-of-the-art studies which validated their prediction accuracy against 10-16 strain gauge measurements. Fracture force was accurately predicted, with the predicted failure location being very close to the experimental fracture rim. Despite the low sample size and the single loading condition tested, the present combined numerical-experimental method showed that finite element models can predict femoral strength by providing a thorough description of the local bone mechanical response.

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Section: Finite Element Modellingmentioning

confidence: 99%

How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements

Grassi

Väänänen

Ristinmaa

et al. 2016

Journal of Biomechanics

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“…[40][41][42][43][44][45][46] In this case, the 3D FE models are generated from the set of slices driven by CT. Generally, the real microarchitecture of the trabecular bone is not considered and the obtained model models are partitioned into trabecular bone and cortical bone continuum regions with the Hounsfield (HU) scale: HU4600 are taken as the cortical region. 47 For simplicity and due to the limited knowledge of the anisotropic behavior of bone, most FE models for bone organs fracture simulation (femur and vertebra mainly) considered the bone tissue as continuum inhomogeneous and isotropic material with empirical assigned material properties based on empirical density-elasticity relationships to every FE of the mesh driven by CT scans.…”

Section: Fea Of Bone Strengthmentioning

confidence: 99%

Osteoporosis drug effects on cortical and trabecular bone microstructure: a review of HR-pQCT analyses

Lespessailles¹,

Hambli

Ferrari

2016

BoneKEy Reports

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With the development of new non-invasive analytical techniques and particularly the advent of high-resolution peripheral quantitative computed tomography (HRpQCT) it is possible to assess cortical and trabecular bone changes under the effects of ageing, diseases and treatments. In the present study, we reviewed the treatment-related effects on bone parameters assessed by HRpQCT imaging. We identified 12 full-length articles published in peer-reviewed journals describing treatment-induced changes assessed by HRpQCT. The design of these studies varied a lot in terms of duration and methodology: some of them were open-labelled, others were double-blind, placebo-controlled or doubleblind, double-dummy, active controlled. In addition, the sample size in these studies ranged from 11 to 324 patients. Motion artifacts occurring during data acquisition were sometimes a real challenge particularly at the radius leading sometimes to exclude the analysis at the radius due to the uninterpretability of microstructural parameters. Responses to therapies were treatment-specific and divergent effects in cortical and trabecular bone with antiresorptive or anabolic agents were observed. Standardization of bone microarchitecture parameters (including porosity) and bone strength estimates by finite element analysis (FEA) are mandatory. The additional value of microarchitecture and FEA estimates changes with therapies in terms of improvement in fracture outcomes which have to be adequately assessed in clinical trials with fracture end point. Data from these reviewed studies advance our understanding of the microstructural consequences of osteoporosis and highlight potential differences in bone quality outcomes within therapies.

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“…[15][16][17][18] As we already mentioned above, an accurate density-elasticity correlation concerning the pelvic bone is not known yet, it has only been determined with indirect methods. [10,15] Nevertheless, our mean elastic modulus values (sacrum 3710 MPa, pelvic bone 4900 MPa) calculated from the cortical-cancellous bone ratio nears those, that can be found in the literature.…”

Section: Discussionmentioning

confidence: 99%

“…The most commonly used method is determination of the elasticity from the density, [10,[15][16][17][18] although such a value explicitly for the pelvis bone has not been determined to date. Recommendations for the most feasible density-elasticity relationship are already available.…”

Section: Objectivesmentioning

confidence: 99%

Further development of our finite element pelvic model to compare fixation methods for pelvic fractures

Sztrinkai¹,

Bodzay²,

Pajor³

et al. 2014

Eklem Hastalik Cerrahisi

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Amaç: Bu çalışmada her türlü kırığın bilgisayarlı simülas-yonuna uygun olan ve güvenilir sonuçlar veren gerçekçi bir model yaratıldı. Hastalar ve yöntemler: İleri numune elde edebilmek için plastik bir pelvis modeli kullanıldı. Veriler sağlıklı bir pelvisin bilgisayarlı tomografi taramasından elde edildi. Üç boyutlu plastik pelvis taraması ile geometrik olarak kesin bir model oluşturuldu. Bilgisayarlı tomografi taramalarından elde edilen verilere göre kemikli kısımların materyal özellikleri modifiye edildi. Pelvis farklı segmentlere ayrıldı ve materyal özelliklerinin doğru olması için her segmentte kortikal ve kansellöz kemik maddesinin oranı tayin edildi. Pelvis modelinin doğrulanmasında, tip C pelvis hasarının simülasyonu yapıldı ve sakrum kırığı ve semfizyoliz plaklar ile stabilize edildi. Bu veriler daha önceki kadavra deneylerinden elde edilen veriler ile karşılaştırıldı. Bulgular: Yeni model üzerinde yapılan simülasyona göre, sakrum kırığının fragmanları arasındaki kayma değerleri, kadavra deneylerinde bildirilen değerlere yakındı ve artan gerilme tolere edilebilir aralıkta kaldı. Sonuç: Yeni sonlu eleman pelvis modelimiz, eski modele göre, pelvisi daha doğru yansıtmaktadır. Modelin doğ-rulaması başarılı olduğundan, güvenilir sonuçlar ile bu yöntem her türlü kırığın bilgisayarlı simülasyonu için uygundur.Anahtar sözcükler: Sonlu eleman analizi; kırık tespiti; pelvis kemiği. Objectives:In this study, we aimed to create a realistic model which is suitable for computerized simulation of any kind of fractures and provides reliable results. Patients and methods: We used a plastic pelvic model to construct advanced specimens. The data were retrieved from the computed tomography scans of a healthy pelvis. A geometrically exact model by the means of three-dimensional scanning of the plastic pelvis was obtained. The material properties of the bony parts based on the data retrieved from the computed tomography scans were modified. The pelvis was divided into distinct segments and the proportion of the cortical and cancellous bone substance in each segment were determined to make the material properties accurate. In the validation of the pelvic model, a type C pelvic injury was simulated and the fracture of the sacrum and the symphyseolysis were stabilized with plates. These data were compared with those of previously performed cadaver experiments. Results: Based on the simulation performed on the new model, the shift values between the fragments of the broken sacrum approximated the reported values of our cadaver experiments and also arising strains remained in the tolerable interval. Conclusion: Our new finite element pelvic model represents the pelvis more accurately than the former one. As the validation of the model was successful, it is suitable for computerized simulation of any kind of fractures offering reliable results.

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The material mapping strategy influences the accuracy of CT-based finite element models of bones: An evaluation against experimental measurements

Cited by 272 publications

References 32 publications

How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements

How accurately can subject-specific finite element models predict strains and strength of human femora? Investigation using full-field measurements

Osteoporosis drug effects on cortical and trabecular bone microstructure: a review of HR-pQCT analyses

Further development of our finite element pelvic model to compare fixation methods for pelvic fractures

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