Identification of elastic properties of human patellae using micro-finite element analysis

Latypova, Adeliya; Maquer, Ghislain Bernard; Elankumaran, Kaliyaperumal; Pahr, Dieter H.; Zysset, Philippe; Pioletti, Dominique P.; Terrier, Alexandre

doi:10.1016/j.jbiomech.2016.07.031

Cited by 8 publications

(7 citation statements)

References 29 publications

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“…The patellar bone has a high degree of anisotropy, with a trabecular architecture adapted to its physiological loading: inferosuperior tension in the anterior part and antero-posterior compression in the posterior part [7] . The overestimation of strain by the isotropic model is probably caused by the loss of stiffness along the main trabecular anisotropic direction.…”

Section: Discussionmentioning

confidence: 99%

“…The strains of each patella were evaluated by an isotropic and an anisotropic validated hFE model [7] , in a non-resurfaced and resurfaced patella option of TKA. The applied boundary conditions were provided by a validated musculoskeletal knee model [10] .…”

Section: Methodsmentioning

confidence: 99%

“…The geometry of each patella was extracted from segmented μCT scans, obtained during a previous study [7] , and imported to Geomagic (Geomagic, Inc., Morrisville, North Carolina, USA) to create non-uniform rational Bspline (NURBS) surfaces. To simulate non-resurfaced cases, we added a cartilage layer for each patella by a uniform extrusion (3 mm) of the posterior articular surface of the patellar bone [6] .…”

Section: Methodsmentioning

confidence: 99%

“…In the isotropic case the fabric tensor M was equal to the identity tensor I . Model parameters were identified and validated using micro finite element (μFE) modeling on 20 cadaveric patellae ( Table 1 ) [7] . In the homogenized isotropic and anisotropic models, the material properties of each bone element were assigned from μCT images using Medtool software ( www.dr-pahr.at ).…”

Section: Methodsmentioning

confidence: 99%

“…of micro-finite element (μFE) modeling of 20 fresh-frozen cadaveric patellae [7] . We considered two alternative models: isotropic and anisotropic.…”

Section: Introductionmentioning

confidence: 99%

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Importance of trabecular anisotropy in finite element predictions of patellar strain after Total Knee Arthroplasty

Latypova

Pioletti

Terrier

2017

Medical Engineering & Physics

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a b s t r a c t Patellar fracture and anterior knee pain remain major complications after Total Knee Arthroplasty (TKA). Patient-specific finite element (FE) models should help improve understanding of these complications through estimation of joint and bone mechanics. However, sensitivity of predictions on modeling techniques and approaches is not fully investigated. In particular, the importance of patellar bone anisotropy, usually omitted in FE models, on strain prediction is still unknown. The objective of this study was thus to estimate the influence of modeling patellar trabecular anisotropy on prediction of patellar strain in TKA models.We compared FE-derived strain predictions with isotopic and anisotropic material properties using 17 validated FE models of the patella after TKA. We considered both non-resurfaced and resurfaced patellae, in a load-bearing TKA joint. We evaluated and compared the bone volume above a strain threshold and, in addition, estimated if the difference in isotopic and anisotropic predictions was consistent between patellae of different average bone volume fraction.Compared to the anisotropic reference, the isotropic prediction of strained volume was 3.7 ± 1.8 times higher for non-resurfaced patellae and 1.5 ± 0.4 times for resurfaced patellae. This difference was higher for patellae with lower average bone volume fraction.This study indicates that strain predictions acquired via isotropic patellar FE models should be interpreted with caution, especially when patellae of different average bone volume fraction are compared.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…of micro-finite element (μFE) modeling of 20 fresh-frozen cadaveric patellae [7] . We considered two alternative models: isotropic and anisotropic.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Importance of trabecular anisotropy in finite element predictions of patellar strain after Total Knee Arthroplasty

Latypova

Pioletti

Terrier

2017

Medical Engineering & Physics

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The effective elastic properties of human trabecular bone may be approximated using micro-finite element analyses of embedded volume elements

Daszkiewicz

Maquer

Zysset

2016

Biomech Model Mechanobiol

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word count: 249 Total word count: 3393Attachments: 5 figures and 2 tables + 1 figure and 4 tables in the appendices 2 Disclosure pageThe authors have no conflict of interest to report. AcknowledgmentsThe script manager Medtool (www.dr-pahr.at) was used to generate the µFE models, start the computations and analyse the results. The authors would like to thank Prof. Bert van Rietbergen for sharing the µCT data. Karol Daszkiewicz is supported by grants from the are also gratefully acknowledged. AbstractBoundary conditions (BCs) and sample size affect the measured elastic properties of cancellous bone. Samples too small to be representative appear stiffer under kinematic uniform BCs (KUBCs) than under periodicity-compatible mixed uniform BCs (PMUBCs). To avoid those effects, we propose to determine the effective properties of trabecular bone using an embedded configuration. Cubic samples of various sizes (2.63, 5.29, 7.96, 10.58 and 15.87 mm) were cropped from µCT scans of femoral heads and vertebral bodies. They were converted into µFE models and their stiffness tensor was established via six uniaxial and shear load cases. PMUBCs-and KUBCs-based tensors were determined for each sample. "In situ" stiffness tensors were also evaluated for the embedded configuration, i.e. when the loads were transmitted to the samples via a layer of trabecular bone. The Zysset-Curnier model accounting for bone volume fraction and fabric anisotropy was fitted to those stiffness tensors and model parameters ν0 (Poisson's ratio), E0 and µ0 (elastic and shear moduli) were compared between sizes. BCs and sample size had little impact on ν0. However, KUBCs-and PMUBCs-based E0 and µ0 respectively decreased and increased with growing size, though convergence was not reached even for our largest samples. Both BCs produced upper and lower bounds for the in situ values that were almost constant across samples dimensions, thus appearing as an approximation of the effective properties. PMUBCs seem also appropriate for mimicking the trabecular core, but they still underestimate its elastic properties (especially in shear) even for nearly orthotropic samples.

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Estimation of the effective yield properties of human trabecular bone using nonlinear micro-finite element analyses

Wili

Maquer

Panyasantisuk

et al. 2017

Biomech Model Mechanobiol

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Micro-finite element ([Formula: see text]FE) analyses are often used to determine the apparent mechanical properties of trabecular bone volumes. Yet, these apparent properties depend strongly on the applied boundary conditions (BCs) for the limited size of volumes that can be obtained from human bones. To attenuate the influence of the BCs, we computed the yield properties of samples loaded via a surrounding layer of trabecular bone ("embedded configuration"). Thirteen cubic volumes (10.6 mm side length) were collected from [Formula: see text]CT reconstructions of human vertebrae and femora and converted into [Formula: see text]FE models. An isotropic elasto-plastic material model was chosen for bone tissue, and nonlinear [Formula: see text]FE analyses of six uniaxial, shear, and multi-axial load cases were simulated to determine the yield properties of a subregion (5.3 mm side length) of each volume. Three BCs were tested. Kinematic uniform BCs (KUBCs: each boundary node is constrained with uniform displacements) and periodicity-compatible mixed uniform BCs (PMUBCs: each boundary node is constrained with a uniform combination of displacements and tractions mimicking the periodic BCs for an orthotropic material) were directly applied to the subregions, while the embedded configuration was achieved by applying PMUBCs on the larger volumes instead. Yield stresses and strains, and element damage at yield were finally compared across BCs. Our findings indicate that yield strains do not depend on the BCs. However, KUBCs significantly overestimate yield stresses obtained in the embedded configuration (+43.1 ± 27.9%). PMUBCs underestimate (-10.0 ± 11.2%), but not significantly, yield stresses in the embedded situation. Similarly, KUBCs lead to higher damage levels than PMUBCs (+51.0 ± 16.9%) and embedded configurations (+48.4 ± 15.0%). PMUBCs are better suited for reproducing the loading conditions in subregions of the trabecular bone and deliver a fair estimation of their effective (asymptotic) yield properties.

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Identification of elastic properties of human patellae using micro-finite element analysis

Cited by 8 publications

References 29 publications

Importance of trabecular anisotropy in finite element predictions of patellar strain after Total Knee Arthroplasty

Importance of trabecular anisotropy in finite element predictions of patellar strain after Total Knee Arthroplasty

The effective elastic properties of human trabecular bone may be approximated using micro-finite element analyses of embedded volume elements

Estimation of the effective yield properties of human trabecular bone using nonlinear micro-finite element analyses

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