Finite element models predict in vitro vertebral body compressive strength better than quantitative computed tomography

Crawford, R. Paul; Cann, Christopher E.; Keaveny, Tony M.

doi:10.1016/s8756-3282(03)00210-2

Cited by 491 publications

(436 citation statements)

References 40 publications

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“…Though the current study was limited to the T10 vertebral level -which has lower fracture incidence compared to other levels such as T8 or L1 [36] -the consistency of our results with previous studies on thoracolumbar vertebrae [4,9] suggests that the tissue in and adjacent to the cortical endplates is involved in the initial failure of thoracolumbar vertebra in general. Finally, our finding that initial failure occurs throughout the vertebra further strengthens the gathering evidence in the literature [11,37,38] that an integrative approach to analyzing the entire vertebral body -by incorporating trabecular bone, cortical endplates and cortical shellmay improve the clinical assessment of aging, disease, and treatment on vertebral strength. Dependence of the relative amount of high-risk tissue on the magnitude of the apparent strain showing that the high-risk tissue first occurred in the trabecular bone.…”

Section: Discussionsupporting

confidence: 78%

Locations of bone tissue at high risk of initial failure during compressive loading of the human vertebral body

Eswaran

Gupta

Keaveny

2007

Bone

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Knowledge of the location of initial regions of failure within the vertebra -cortical shell, cortical endplates vs. trabecular bone, as well as anatomic location -may lead to improved understanding of the mechanisms of aging, disease and treatment. The overall objective of this study was to identify the location of the bone tissue at highest risk of initial failure within the vertebral body when subjected to compressive loading. Toward this end, micro-CT based 60-micron voxel-sized, linearly elastic, finite element models of a cohort of thirteen elderly (age range: 54-87 years, 75 ± 9 years) female whole vertebrae without posterior elements were virtually loaded in compression through a simulated disc. All bone tissue within each vertebra having either the maximum or minimum principal strain beyond its 90 th percentile was defined as the tissue at highest risk of initial failure within that particular vertebral body. Our results showed that such high-risk tissue first occurred in the trabecular bone and that the largest proportion of the high-risk tissue also occurred in the trabecular bone. The amount of high-risk tissue was significantly greater in and adjacent to the cortical endplates than in the mid-transverse region. The amount of high-risk tissue in the cortical endplates was comparable to or greater than that in the cortical shell regardless of the assumed Poisson's ratio of the simulated disc. Our results provide new insight into the micromechanics of failure of trabecular and cortical bone within the human vertebra, and taken together, suggest that during strenuous compressive loading of the vertebra, the tissue near and including the endplates is at the highest risk of initial failure.

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Section: Discussionsupporting

confidence: 78%

Locations of bone tissue at high risk of initial failure during compressive loading of the human vertebral body

Eswaran

Gupta

Keaveny

2007

Bone

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“…Numerous researchers have speculated that DXA is an inaccurate measure of vertebral fracture risk potential because it is structurally simplistic, i.e., it reflects only volume averaged material properties, and they have focused their efforts on developing more sophisticated mechanical models of vertebral body fractures (2,8,9,14,15,19,23,36). These patient-specific models are generated from quantitative computed tomography (QCT) scans and can be classified as: 1) relatively simplistic "mechanics of solids" (MOS) models (2,8,9,14,36), such as minimum axial rigidity and stiffness, or 2) three dimensional finite element (FE) models (8,9,15,19,23). Clinical use of such techniques is still under investigation as there is no clear evidence that these methods have better outcomes than DXA-BMD in vivo.…”

Section: Introductionmentioning

confidence: 99%

“…Finite element (FE) models derived from QCT scans are a promising alternative to BMD and MOS techniques since these models automatically incorporate bone geometry and material heterogeneity (8,15,19) and may be used to simulate various loading conditions (7)(8)(9)32). Studies have shown that QCT-based finite element predictions of vertebral strength better discriminate between osteoporotic and non-osteoporotic individuals (15) and well predict the experimental strength of lumbar vertebrae (8).…”

Section: Introductionmentioning

confidence: 99%

“…Studies have shown that QCT-based finite element predictions of vertebral strength better discriminate between osteoporotic and non-osteoporotic individuals (15) and well predict the experimental strength of lumbar vertebrae (8). Crawford et al, (8) found that QCT-based finite element stiffness was a better predictor of vertebral compressive strength (R 2 = 0.86) than either trabecular bone mineral density (tBMD) (R 2 = 0.53) or axial rigidity (R 2 = 0.65). Although this result is promising for the continued development of the finite element technique, the data set used in this study was extremely small (N = 13), and only a subset of the possible BMD and MOS metrics were used for comparison.…”

Section: Introductionmentioning

confidence: 99%

“…This method is the testing paradigm for new non-invasive strength assessment techniques (5,(12)(13)(14)25,28,33) because it ensures well-defined, repeatable loading conditions. Radiographic information was taken exclusively from QCT scans, and our predictive measures were a subset of those most frequently used in the literature (2,8,9,14,36). Lastly, we tested a large number of samples (N = 81 with 4 excluded from analysis) from a high-risk fracture region (T6 to T10) (6) of predominantly female, elderly donors in order to lend statistical credibility to our findings regarding the relative abilities of these QCT-based techniques to predict osteoporotic fractures in vivo.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of quantitative computed tomography-based measures in predicting vertebral compressive strength

Buckley

Loo

Motherway

2007

Bone

142

121

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Patient-specific measures derived from quantitative computed tomography (QCT) scans are currently being developed as a clinical tool for vertebral strength prediction. QCT-based measurement techniques vary greatly in structural complexity and generally fall into one of three categories: 1) bone mineral density (BMD), 2) "mechanics of solids" (MOS) models, such as minimum axial rigidity (the product of axial stiffness and vertebral height), or 3) three dimensional finite element (FE) models. There is no clear consensus as to the relative performance of these measures due to differences in experimental protocols, sample sizes and demographics, and outcome metrics. The goal of this study was to directly compare the performance of QCT-based assessment techniques of varying degrees of structural sophistication in predicting experimental vertebral compressive strength. Eighty-one human thoracic vertebrae (T6 -T10) from 44 donors cadavers (F = 32, M = 12; 85 + 8 y.o., max = 97 y.o., min = 54 y.o.) were QCT scanned and destructively tested in uniaxial compression. The QCT scans were processed to generate FE models and various BMD and MOS measures, including trabecular bone mineral density (tBMD), integral bone mineral density (iBMD), and axial rigidity. Bone mineral density was weakly to moderately predictive of compressive strength (R 2 = 0.16 and 0.62 for tBMD and iBMD, respectively). Ex vivo vertebral strength was strongly correlated with both axial rigidity (R 2 = 0.81) and FE strength measurements (R 2 = 0.80), and the predictive capabilities of these two metrics were statistically equivalent (p > 0.05 for differences between FE and axial rigidity). The results of this study indicate that non-invasive predictive measures of vertebral strength should include some level of structural sophistication, specifically, gross geometric and material property distribution information. However, for uniaxial compression of isolated vertebrae, which is the current biomechanical testing paradigm for new non-invasive strength assessment techniques, QCT-based FE and axial rigidity measures are equivalent predictors of experimental strength. However, before abandoning the FE method in favor of more simplistic techniques, future work should investigate the performance of the FE method versus MOS measures for more physiologically representative loading conditions, e.g., anterior bending or in situ loading with intervertebral discs intact.

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High-Trauma Fractures and Bone Mineral Density

Khosla

2007

JAMA

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Finite element models predict in vitro vertebral body compressive strength better than quantitative computed tomography

Cited by 491 publications

References 40 publications

Locations of bone tissue at high risk of initial failure during compressive loading of the human vertebral body

Locations of bone tissue at high risk of initial failure during compressive loading of the human vertebral body

Comparison of quantitative computed tomography-based measures in predicting vertebral compressive strength

High-Trauma Fractures and Bone Mineral Density

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