Experimental validation of intact and implanted distal femur finite element models

Completo, António; Fonseca, Fernando; Simões, José Augusto

doi:10.1016/j.jbiomech.2006.11.012

Cited by 38 publications

(27 citation statements)

References 31 publications

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“…The standard deviations of principal strains obtained in this study were in the range of those calculated in the other experimental studies with synthetic femurs (e.g. Completo et al, 2007;Completo et al, 2008;Cristofolini and Viceconti, 1996;Viceconti et al, 2001;Waide et al, 2003).…”

Section: Discussionsupporting

confidence: 74%

“…Several experimental studies with composite bones were carried out involving the measurement of bone surface strains. The main purpose of these was to respond to a clinical need in order to investigate in vitro implant-bone load transfer mechanisms, monitoring the strain shielding effect and for finite element model validation (Completo et al, 2007(Completo et al, , 2008Cristofolini and Viceconti, 1996;Viceconti et al, 2001;Waide et al, 2003). The standard deviations of principal strains obtained in this study were in the range of those calculated in the other experimental studies with synthetic femurs (e.g.…”

Section: Discussionmentioning

confidence: 67%

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Strain shielding in distal femur after patellofemoral arthroplasty under different activity conditions

Meireles

Completo

Simões

et al. 2010

Journal of Biomechanics

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Strain shielding, a mechanical effect occurring in structures combining stiff with more flexible materials, is considered to lead to a reduction of density in bone surrounding the implant. This effect can be related to the weakness of the implant fixation, which can promote implant loosening. Several studies describe a significant decrease in postoperative bone mineral density adjacent to joint implants, which can compromise their long-term fixation. The aim of the present study was to quantify the strain shielding effect on the distal femur after patellofemoral arthroplasty. For this purpose three activities of daily living were considered: level walking, stair climbing and deep bending at different angles of knee flexion. To determine the strain shielding effect, cortical bone strains were measured experimentally with triaxial strain gauges in synthetic femurs before and after patellofemoral arthroplasty for each of the different daily activities. The results showed that the patellofemoral arthroplasty in general reduced the strains in the medial and distal regions of the femur when deep bending activity occurred, consequently, strain shielding in these regions, with strain decreases of -72.0% and -67.5% were measured. On the other side, higher values of strain were found in the anterior region after patellofemoral replacement for this activity with an increase of +182.0%. The occurrence of strain shielding seems to be more significant when the angle of knee flexion and applied load increases. Strain shielding and over-loading may have relevant effects on bone remodeling surrounding the patellofemoral implant, suggesting a potential effect of later bone resorption in the medial and distal femur regions in case of regular deep bending activity.

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Section: Discussionsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 67%

Strain shielding in distal femur after patellofemoral arthroplasty under different activity conditions

Meireles

Completo

Simões

et al. 2010

Journal of Biomechanics

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“…In this study was applied an identical experimental method described by Completo et al [24], with others synthetic models and strain measuring before and after implantation in the same femur model. Three synthetic femurs (third generation, left, mod.…”

Section: Methodsmentioning

confidence: 99%

“…Completo et al [24], on a previous experimental-numerical validation study measured strains in distal synthetic femur and compared to those obtained with numerical models, but did not compare strains changes (strain-shielding) before and after components implantation in the same femur model. The goal of the present study was to measure strain shielding in distal synthetic femurs with three different constructs of TKA.…”

Section: Introductionmentioning

confidence: 99%

Experimental Evaluation of Strain Shielding in Distal Femur in Revision TKA

2007

Self Cite

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Theoretical concerns about the use of cemented and press-fit stems in revision total knee arthroplasty (TKA) include stress shielding with adverse effects on prosthesis fixation. Radiological studies have showed distal femoral bone resorption after revision TKA. The revision with use of stems can place abnormal stresses. These stresses can promote the effect of bone stress shielding and may contribute to bone loss. Experimental quantification of strain shielding in the distal synthetic femur following TKA is the main purpose of the present study. Three different constructs of TKA were assessed. The first construct included a stemless femoral component. The other two included a press-fit and a cemented femoral stem. Cortical bone strains were measured experimentally with tri-axial strain gauges in synthetic femurs before and after in-vitro knee surgery. The difference between principal strains of implanted and intact femur was calculated for each strain gauge position. This study indicates that the use of stems in distal femur changes the distribution and magnitude of bone strains. The press-fit stem provoked relevant bone area (stem length) subjected to strain shielding and also originated the highest reduction of strains in the distal region, which can potentially induce bone resorption. The stemless implanted femur produced minor bone strain changes relatively to the intact femur. The use of distal femur stems increases initial stability in the bone, but the observed reduction of strains in this region, relative to the intact femur, provokes strain shielding that can induce bone resorption and may compromise the long term implant stability.

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“…Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft 1 INTRODUCTION Numerous previous finite element (FE) studies have investigated the biomechanics of bone with orthopaedic implants; for example, fracture fixation [1][2][3], vertebral fixation [4], hip arthroplasty [5], and knee prostheses [6][7][8]. Depending on the outcome of interest, the results of such FE simulations may depend upon the specified elastic constants of bone tissues.…”

mentioning

confidence: 99%

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

Donaldson

Pankaj

Cooper

et al. 2011

Proc Inst Mech Eng H

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Homogenized elastic properties are often assumed for macro-finite element (FE) models used in orthopaedic biomechanics. The accuracy of material property assignments may have a strong effect on the ability of these models to make accurate predictions. For cortical bone, most macro-scale FE models assume isotropic elastic material behaviour and do not include variation of material properties due to bone micro-architecture. The first aim of the present study was to evaluate the variation of apparent-level (homogenized) orthotropic elastic constants of cortical bone with age and indices of bone micro-architecture. Considerable age-dependent differences in porosity were noted across the cortical thickness in previous research. The second aim of the study was to quantify the resulting differences in elastic constants between the periosteum and endosteum. Specimens were taken from the anterior femoral midshaft of 27 female donors (age 53.4 +/- 23.6 years) and micro-FE (gFE) analysis was used to derive orthotropic elastic constants. The variation of orthotropic elastic constants (Young's moduli, shear moduli, and Poisson's ratios) with various cortical bone micro-architectural indices was investigated. The ratio of canal volume to tissue volume, Ca.V/TV, analogous to porosity, was found to be the strongest predictor (r2(ave) = 0.958) of the elastic constants. Age was less predictive (r2(ave) = 0.385) than Ca.V/TV. Elastic anisotropy increased with increasing Ca.V/TV, leading to lower elastic moduli in the transverse, typically less frequently loaded, directions. Increased Ca.V/TV led to a more substantial reduction in elastic constants at the endosteal aspect than at the periosteal aspect. The results are expected to be most applicable in similar midshaft locations of long bones; specific analysis of other sites would be necessary to evaluate elastic properties elsewhere. It was concluded that Ca.V/TV was the most predictive of cortical bone elastic constants and that considerable periosteal-endosteal variations in these constants can develop with bone loss.

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Experimental validation of intact and implanted distal femur finite element models

Cited by 38 publications

References 31 publications

Strain shielding in distal femur after patellofemoral arthroplasty under different activity conditions

Strain shielding in distal femur after patellofemoral arthroplasty under different activity conditions

Experimental Evaluation of Strain Shielding in Distal Femur in Revision TKA

Relating age and micro-architecture with apparent-level elastic constants: a micro-finite element study of female cortical bone from the anterior femoral midshaft

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