In vitro replication of spontaneous fractures of the proximal human femur

Cristofolini, Luca; Juszczyk, Mateusz; Martelli, Saulo; Taddei, Fulvia; Viceconti, Marco

doi:10.1016/j.jbiomech.2007.03.015

Cited by 119 publications

(162 citation statements)

References 45 publications

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“…Another limitation is associated with the relatively slow loading rate of 0.17 mm s −1 (168 mstrain s −1 ), which is one order of magnitude slower than the former reported physiological rates (2 mm s −1 for example in Cristofolini et al (2007)). The slow strain rate may have been attributed to a more pronounced viscoelastic effect, enlarging the region beyond 'yielding'.…”

Section: Discussionmentioning

confidence: 92%

Predicting the yield of the proximal femur using high-order finite-element analysis with inhomogeneous orthotropic material properties

Yosibash

Tománek

Trabelsi

2010

Phil. Trans. R. Soc. A.

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High-order finite-element (FE) analyses with inhomogeneous isotropic material properties have been shown to predict the strains and displacements on the surface of the proximal femur with high accuracy when compared with in vitro experiments. The same FE models with inhomogeneous orthotropic material properties produce results similar to those obtained with isotropic material properties. Herein, we investigate the yield prediction capabilities of these models using four different yield criteria, and the spread in the predicted load between the isotropic and orthotropic material models. Subjectspecific high-order FE models of two human femurs were generated from CT scans with inhomogeneous orthotropic or isotropic material properties, and loaded by a simple compression force at the head. Computed strains and stresses by both the orthotropic and isotropic FE models were used to determine the load that predicts 'yielding' by four different 'yield criteria': von Mises, Drucker-Prager, maximum principal stress and maximum principal strain. One of the femurs was loaded by a simple load until fracture, and the force resulting in yielding was compared with the FE predicted force. The surface average of the 'maximum principal strain' criterion in conjunction with the orthotropic FE model best predicts both the yield force and fracture location compared with other criteria. There is a non-negligible influence on the predictions if orthotropic or isotropic material properties are applied to the FE model. All stress-based investigated 'yield criteria' have a small spread in the predicted failure. Because only one experiment was performed with a rather simplified loading configuration, the conclusions of this work cannot be claimed to be either reliable or sufficient, and future experiments should be performed to further substantiate the conclusions.

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Section: Discussionmentioning

confidence: 92%

Predicting the yield of the proximal femur using high-order finite-element analysis with inhomogeneous orthotropic material properties

Yosibash

Tománek

Trabelsi

2010

Phil. Trans. R. Soc. A.

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“…First, the femoral neck fracture scenario was analysed in stumbling, by applying a joint contact force (JCF) to the femoral head at 8° adduction representing the worst case loading condition identified from a cadaver study [32].…”

Section: Methodsmentioning

confidence: 99%

Performance of the resurfaced hip. Part 1: The influence of the prosthesis size and positioning on the remodelling and fracture of the femoral neck

Dickinson

Taylor²,

Browne

2009

Proc Inst Mech Eng H

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Abstract:Hip Resurfacing is an established treatment for osteoarthritis in young, active patients. Failure modes include femoral neck fracture and prosthesis loosening, which may be associated with medium term bone adaptation, including femoral neck narrowing and densification around the prosthesis stem.Finite Element modelling was used to indicate the effects of prosthesis sizing and positioning on bone remodelling and fracture strength under a range of normal and traumatic loads, aiming to understand these failure modes better.The simulations predicted increased superior femoral neck stress shielding in young patients with small prostheses, which required shortening of the femoral neck to give an acceptable implant-bone interface.However with a larger prosthesis, natural femoral head centre recreation in the implanted state was possible, so stress shielding was restricted to the prosthesis interior, and its extent was less sensitive to prosthesis orientation. With valgus orientation, the implanted neck strength was, at worst, within 3% of its intact strength.The study suggests that femoral neck narrowing may be linked to a reduction in horizontal femoral offset, occurring if the prosthesis is excessively undersized. As such, hip resurfacing should aim to reproduce the natural femoral head centre, and for valgus prosthesis orientation to avoid femoral neck fracture.

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“…The maximum risk of fracture corresponded to a force tilted by 8°in the frontal plane and neutral in a sagittal plane. Finally, the in vitro loading set-up was designed based on the indications from the FE model, where the load was applied in the direction that caused the highest risk of fractures in the region of interest (Cristofolini et al 2007a). …”

Section: (A) Identification Of Most Relevant Loading Configuration(s)mentioning

confidence: 99%

“…-The most relevant loading configurations to replicate spontaneous fractures (Cristofolini et al 2007a) and to measure implant-bone micromotions in resurfacing hip prostheses (Cristofolini et al 2007c) were chosen based on dedicated FE analyses (figure 7). -An indication about the need for simulating (or not simulating) the action of the abductor muscles during in vitro replication of spontaneous fractures was obtained from FE models (Cristofolini et al 2007a).…”

Section: A Success Story: Integrated Investigation Of the Proximal Humentioning

confidence: 99%

“…-The strain distribution on the bone surface can be investigated either using strain gauges (Huiskes et al 1981;Field & Rushton 1989;Cristofolini et al 2009b), or photoelasticity (Zhou et al 1990;Slemon et al 1991;Cotton et al 1994;Cristofolini et al 1994;Peindl et al 2004), or alternative optical techniques (Duncan 1992). -The strength and/or mode of failure of whole bones (Martens et al 1986;Yang et al 1996;Lochmüller et al 2002;Cristofolini et al 2007a). …”

Section: Introductionmentioning

confidence: 99%

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Mechanical testing of bones: the positive synergy of finite–element models andin vitroexperiments

Cristofolini

Schileo

Juszczyk

et al. 2010

Phil. Trans. R. Soc. A.

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Bone biomechanics have been extensively investigated in the past both with in vitro experiments and numerical models. In most cases either approach is chosen, without exploiting synergies. Both experiments and numerical models suffer from limitations relative to their accuracy and their respective fields of application. In vitro experiments can improve numerical models by: (i) preliminarily identifying the most relevant failure scenarios; (ii) improving the model identification with experimentally measured material properties; (iii) improving the model identification with accurately measured actual boundary conditions; and (iv) providing quantitative validation based on mechanical properties (strain, displacements) directly measured from physical specimens being tested in parallel with the modelling activity. Likewise, numerical models can improve in vitro experiments by: (i) identifying the most relevant loading configurations among a number of motor tasks that cannot be replicated in vitro; (ii) identifying acceptable simplifications for the in vitro simulation; (iii) optimizing the use of transducers to minimize errors and provide measurements at the most relevant locations; and (iv) exploring a variety of different conditions (material properties, interface, etc.) that would require enormous experimental effort. By reporting an example of successful investigation of the femur, we show how a combination of numerical modelling and controlled experiments within the same research team can be designed to create a virtuous circle where models are used to improve experiments, experiments are used to improve models and their combination synergistically provides more detailed and more reliable results than can be achieved with either approach singularly.

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In vitro replication of spontaneous fractures of the proximal human femur

Cited by 119 publications

References 45 publications

Predicting the yield of the proximal femur using high-order finite-element analysis with inhomogeneous orthotropic material properties

Predicting the yield of the proximal femur using high-order finite-element analysis with inhomogeneous orthotropic material properties

Performance of the resurfaced hip. Part 1: The influence of the prosthesis size and positioning on the remodelling and fracture of the femoral neck

Mechanical testing of bones: the positive synergy of finite–element models andin vitroexperiments

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