Biomechanical Role of Bone Anisotropy Estimated on Clinical CT Scans by Image Registration

Taghizadeh, Elham; Zysset, Philippe; Latypova, Adeliya; Terrier, Alexandre; Büchler, Philippe

doi:10.1007/s10439-016-1551-4

Cited by 20 publications

(20 citation statements)

References 33 publications

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“…When only low-resolution images are available, such as clinical CT scans, the isotropic model is a reasonable alternative. The anisotropic model might still be applicable by estimating anisotropy with recently proposed approaches, such as database approach or μCT template registration (Marangalou et al, 2013;Taghizadeh et al, 2016).…”

Section: Discussionmentioning

confidence: 99%

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

Latypova

Maquer²,

Elankumaran

et al. 2016

Journal of Biomechanics

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a b s t r a c tCurrent homogenized finite element (hFE) models of the patella lack a validated material law and mostly overlook trabecular anisotropy. The objective of this study was to identify the elastic constants of patellar trabecular bone. Using μCT scans of 20 fresh-frozen cadaveric patellae, we virtually extracted 200 trabecular cubes (5.3 mm side length). Bone volume fraction and fabric tensor were measured. The elastic constants were identified from six independent load cases using micro finite element (μFE) analyses. Both anisotropic and isotropic material laws were considered. The elastic constants were validated by comparing stiffness, strain and stress between hFE and μFE predictions of 18 patellar sections and six load cases. The hFE section models were built from μCT (anisotropic law) and CT (isotropic law) scans.The homogenized anisotropic model induced less error (13 7 5%) in the global stiffness prediction than the isotropic one (18 7 6%), and less error in the prediction of local apparent strain, stress, and strain energy, compared to the isotropic one. This validated hFE model could be used for future applications, either with the anisotropic constants, or with the isotropic ones when the trabecular fabric is unavailable.

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Section: Discussionmentioning

confidence: 99%

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

Latypova

Maquer²,

Elankumaran

et al. 2016

Journal of Biomechanics

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“…Interestingly, while a single template was used to estimate bone anisotropy, the prediction error was in the same range as for the studies that employed a dataset of high-resolution scans [11]. This result questions the variability of bone anisotropy…”

Section: Introductionmentioning

confidence: 95%

“…A dataset of 73 proximal femurs [16] was used to build a statistical model of bone [11,16]. The shafts of all samples were cropped such that they all have the same ratio between the shaft length and the neck length [9].…”

Section: Datasetmentioning

confidence: 99%

“…Other studies rely on existing high-resolution scans to estimate the fabric tensor for clinical CT. Hazrati and colleagues employed a database of high-resolution scans and assigned to the patient's bone the anisotropy of the closest instance in a pre-existing database. A similar study has been conducted where a single template anisotropy was morphed into the shape of the patient's bone [11].…”

Section: Introductionmentioning

confidence: 99%

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Statistical analysis of the inter-individual variations of the bone shape, volume fraction and fabric and their correlations in the proximal femur

Taghizadeh

Chandran

Zysset

et al. 2017

Bone

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Including structural information of trabecular bone improves the prediction of bone strength and fracture risk. However, this information is available in clinical CT scans, only for peripheral bones. We hypothesized that a correlation exists between the shape of the bone, its volume fraction (BV/TV) and fabric, which could be characterized using statistical modeling. High-resolution peripheral computed tomography (HR-pQCT) images of 73 proximal femurs were used to build a combined statistical model of shape, BV/TV and fabric. The model was based on correspondence established by image registration and by morphing of a finite element mesh describing the spatial distribution of the bone properties. Results showed no correlation between the distribution of bone shape, BV/TV and fabric. Only the first mode of variation associated with density and orientation showed a strong relationship (R>0.8). In addition, the model showed that the anisotropic information of the proximal femur does not vary significantly in a population of healthy, osteoporotic and osteopenic samples. In our dataset, the average anisotropy of the population was able to provide a close approximation of the patient-specific anisotropy. These results were confirmed by homogenized finite element (hFE) analyses, which showed that the biomechanical behavior of the proximal femur was not significantly different when the average anisotropic information of the population was used instead of patient-specific fabric extracted from HR-pQCT. Based on these findings, it can be assumed that the fabric information of the proximal femur follows a similar structure in an elderly population of healthy, osteopenic and osteoporotic proximal femurs.

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“…Therefore, patellar isotropic models should be used with caution and account for possible inaccuracy. Alternatively, when bone anisotropy cannot be measured directly, a generic or statistical map of anisotropy could be applied to the patella [23] or it can be obtained with template registration approach [24] .…”

Section: Discussionmentioning

confidence: 99%

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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Biomechanical Role of Bone Anisotropy Estimated on Clinical CT Scans by Image Registration

Cited by 20 publications

References 33 publications

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

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

Statistical analysis of the inter-individual variations of the bone shape, volume fraction and fabric and their correlations in the proximal femur

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

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