Biofidelic finite element models for accurately classifying hip fracture in a retrospective clinical study of elderly women from the AGES Reykjavik cohort

Enns-Bray, William S.; Bahaloo, Hassan; Fleps, Ingmar; Pauchard, Yves; Taghizadeh, Elham; Sigurðsson, Sigurður; Aspelund, Thor; Büchler, Philippe; Harris, Tamara B.; Gudnason, Vilmundur; Ferguson, Stephen J.; Pálsson, Halldór; Helgason, Benedikt

doi:10.1016/j.bone.2018.09.014

Cited by 27 publications

(26 citation statements)

References 59 publications

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“…As a new modality for osteoporosis testing, and given its biomechanical and mechanistic nature, BCT is likely to evolve. As summarized elsewhere [24,26], further improvements to BCT for measuring bone strength clinically might result from incorporating such characteristics as trabecular orientation, enhanced cortical modeling, effects of aging on bone tissue ductility, and multiple sideway fall loading conditions-all topics of ongoing research [42,97,99,100,116]. In addition, beyond bone strength, other biomechanical factors are also important in fracture etiology: for example, fall risk, fall biomechanics, probabilistic loading, muscle strength, overall skeletal geometry, and soft tissue-related energy absorption and force attenuation [41].…”

Section: Summary and Discussionmentioning

confidence: 99%

Biomechanical Computed Tomography analysis (BCT) for clinical assessment of osteoporosis

et al. 2020

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The surgeon general of the USA defines osteoporosis as "a skeletal disorder characterized by compromised bone strength, predisposing to an increased risk of fracture." Measuring bone strength, Biomechanical Computed Tomography analysis (BCT), namely, finite element analysis of a patient's clinical-resolution computed tomography (CT) scan, is now available in the USA as a Medicare screening benefit for osteoporosis diagnostic testing. Helping to address under-diagnosis of osteoporosis, BCT can be applied "opportunistically" to most existing CT scans that include the spine or hip regions and were previously obtained for an unrelated medical indication. For the BCT test, no modifications are required to standard clinical CT imaging protocols. The analysis provides measurements of bone strength as well as a dual-energy X-ray absorptiometry (DXA)equivalent bone mineral density (BMD) T-score at the hip and a volumetric BMD of trabecular bone at the spine. Based on both the bone strength and BMD measurements, a physician can identify osteoporosis and assess fracture risk (high, increased, not increased), without needing confirmation by DXA. To help introduce BCT to clinicians and health care professionals, we describe in this review the currently available clinical implementation of the test (VirtuOst), its application for managing patients, and the underlying supporting evidence; we also discuss its main limitations and how its results can be interpreted clinically. Together, this body of evidence supports BCT as an accurate and convenient diagnostic test for osteoporosis in both sexes, particularly when used opportunistically for patients already with CT.

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Section: Summary and Discussionmentioning

confidence: 99%

Biomechanical Computed Tomography analysis (BCT) for clinical assessment of osteoporosis

et al. 2020

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“…One limitation of the Contact model is the assumption of a direct contact between the bone and ground. This does not consider the soft tissue surrounding the greater trochanter, which is likely to have some damping effects and absorb some energy upon impact (Enns-bray et al, 2019;Kerrigan et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

“…FE models can predict the mechanical strength of a femur as measured experimentally on a cadaveric bone under simulated side-fall conditions with excellent accuracy (Grassi et al, 2012;Pottecher et al, 2016;Schileo et al, 2014). However, the stratification power (the ability to separate fractured cases from controls) appears only slightly better than the aBMD (Enns-bray et al, 2019;Keyak et al, 2011;Kopperdahl et al, 2014;Nishiyama et al, 2014;Orwoll et al, 2009). Similarly, in a retrospective study carried out at our Institute on the same cohort used in this study, the stratification power of femur strength under side-fall conditions was 79% compared with 75% for aBMD (Qasim et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

The effect of boundary and loading conditions on patient classification using finite element predicted risk of fracture

Altai

Qasim

et al. 2019

Clinical Biomechanics

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Background: Osteoporotic proximal femoral fractures associated to falls are a major health burden in the ageing society. Recently, bone strength estimated by finite element models emerged as a feasible alternative to areal bone mineral density as a predictor of fracture risk. However, previous studies showed that the accuracy of patients' classification under their risk of fracture using finite element strength when simulating posterolateral falls is only marginally better than that of areal bone mineral density. Patients tend to fall in various directions: since the predicted strength is sensitive to the fall direction, a prediction based on certain fall directions might not be fully representative of the physical event. Hence, side fall boundary conditions may not be completely representing the physical event. Methods: The effect of different side fall boundary and loading conditions on a retrospective cohort of 98 postmenopausal women was evaluated to test models' ability to discriminate fracture and control cases. Three different boundary conditions (Linear, Multi-point constraints and Contact model) were investigated under various anterolateral and posterolateral falls. Findings: The stratification power estimated by the area under the receiver operating characteristic curve was highest for Contact model (0.82), followed by Multi-point constraints and Linear models with 0.80. Both Contact and MPC models predicted high strains in various locations of the proximal femur including the greater trochanter, which has rarely reported previously. Interpretation: A full range of fall directions and less restrictive displacement constraints can improve the finite element strength ability to classify patients under their risk of fracture.

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“…The fracture status in the FEMs was assessed based on the fragility ratio (FR), which was calculated by dividing the peak force derived from the FE linear models by the peak force derived from the FE nonlinear models. (Equation )

FR = \frac{F_{p e a k} false({FE}_{linear} false)}{F_{p e a k} false({FE}_{non - linear} false)}

…”

Section: Methodsmentioning

confidence: 99%

Explicit Finite Element Models Accurately Predict Subject-Specific and Velocity-Dependent Kinetics of Sideways Fall Impact

Fleps

Guy

Ferguson

et al. 2019

Journal of Bone and Mineral Research

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The majority of hip fractures in the elderly are the result of a fall from standing or from a lower height. Current injury models focus mostly on femur strength while neglecting subject-specific loading. This article presents an injury modeling strategy for hip fractures related to sideways falls that takes subject-specific impact loading into account. Finite element models (FEMs) of the human body were used to predict the experienced load and the femoral strength in a single model. We validated these models for their predicted peak force, effective pelvic stiffness, and fracture status against matching ex vivo sideways fall impacts (n = 11) with a trochanter velocity of 3.1 m/s. Furthermore, they were compared to sideways impacts of volunteers with lower impact velocities that were previously conducted by other groups. Good agreement was found between the ex vivo experiments and the FEMs with respect to peak force (root mean square error [RMSE] = 10.7%, R 2 = 0.85) and effective pelvic stiffness (R 2 = 0.92, RMSE = 12.9%). The FEMs were predictive of the fracture status for 10 out of 11 specimens. Compared to the volunteer experiments from low height, the FEMs overestimated the peak force by 25% for low BMI subjects and 8% for high BMI subjects. The effective pelvic stiffness values that were derived from the FEMs were comparable to those derived from impacts with volunteers. The force attenuation from the impact surface to the femur ranged between 27% and 54% and was highly dependent on soft tissue thickness (R 2 = 0.86). The energy balance in the FEMS showed that at the time of peak force 79% to 93% of the total energy is either kinetic or was transformed to soft tissue deformation. The presented FEMs allow for direct discrimination between fracture and nonfracture outcome for sideways falls and bridge the gap between impact testing with volunteers and impact conditions representative of real life falls. Specimens: n = 11 (6 female, 5 male). BMI = body mass index (subject weight divided by the subject height squared); T ST,GT = thickness of soft tissue over the greater trochanter; aBMD total hip = areal bone mineral density of the proximal femur.

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Biofidelic finite element models for accurately classifying hip fracture in a retrospective clinical study of elderly women from the AGES Reykjavik cohort

Cited by 27 publications

References 59 publications

Biomechanical Computed Tomography analysis (BCT) for clinical assessment of osteoporosis

Biomechanical Computed Tomography analysis (BCT) for clinical assessment of osteoporosis

The effect of boundary and loading conditions on patient classification using finite element predicted risk of fracture

Explicit Finite Element Models Accurately Predict Subject-Specific and Velocity-Dependent Kinetics of Sideways Fall Impact

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