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Subject-specific FE models of the human femur predict fracture path and bone strength under single-leg-stance loading

Gustafsson, Anna LU ; Tognini, Martina ; Bengtsson, Frida ; Gasser, T. Christian ; Isaksson, Hanna LU and Grassi, Lorenzo LU (2021) In Journal of the Mechanical Behavior of Biomedical Materials 113.
Abstract

Hip fractures are a major health problem with high socio-economic costs. Subject-specific finite element (FE) models have been suggested to improve the fracture risk assessment, as compared to clinical tools based on areal bone mineral density, by adding an estimate of bone strength. Typically, such FE models are limited to estimate bone strength and possibly the fracture onset, but do not model the fracture process itself. The aim of this study was to use a discrete damage approach to simulate the full fracture process in subject-specific femur models under stance loading conditions. A framework based on the partition of unity finite element method (PUFEM), also known as XFEM, was used. An existing PUFEM framework previously used on a... (More)

Hip fractures are a major health problem with high socio-economic costs. Subject-specific finite element (FE) models have been suggested to improve the fracture risk assessment, as compared to clinical tools based on areal bone mineral density, by adding an estimate of bone strength. Typically, such FE models are limited to estimate bone strength and possibly the fracture onset, but do not model the fracture process itself. The aim of this study was to use a discrete damage approach to simulate the full fracture process in subject-specific femur models under stance loading conditions. A framework based on the partition of unity finite element method (PUFEM), also known as XFEM, was used. An existing PUFEM framework previously used on a homogeneous generic femur model was extended to include a heterogeneous material description together with a strain-based criterion for crack initiation. The model was tested on two femurs, previously mechanically tested in vitro. Our results illustrate the importance of implementing a subject-specific material distribution to capture the experimental fracture pattern under stance loading. Our models accurately predicted the fracture pattern and bone strength (1% and 5% error) in both investigated femurs. This is the first study to simulate complete fracture paths in subject-specific FE femur models and it demonstrated how discrete damage models can provide a more complete picture of fracture risk by considering both bone strength and fracture toughness in a subject-specific fashion.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Cohesive traction separation law, Crack propagation, Crack surface, Partition of unity, PUFEM, XFEM
in
Journal of the Mechanical Behavior of Biomedical Materials
volume
113
article number
104118
publisher
Elsevier
external identifiers
  • scopus:85093960152
  • pmid:33125949
ISSN
1751-6161
DOI
10.1016/j.jmbbm.2020.104118
language
English
LU publication?
yes
id
bd0f620d-f1d5-4329-a5dc-47003c47fa66
date added to LUP
2020-11-04 10:40:59
date last changed
2021-06-20 03:08:59
@article{bd0f620d-f1d5-4329-a5dc-47003c47fa66,
  abstract     = {<p>Hip fractures are a major health problem with high socio-economic costs. Subject-specific finite element (FE) models have been suggested to improve the fracture risk assessment, as compared to clinical tools based on areal bone mineral density, by adding an estimate of bone strength. Typically, such FE models are limited to estimate bone strength and possibly the fracture onset, but do not model the fracture process itself. The aim of this study was to use a discrete damage approach to simulate the full fracture process in subject-specific femur models under stance loading conditions. A framework based on the partition of unity finite element method (PUFEM), also known as XFEM, was used. An existing PUFEM framework previously used on a homogeneous generic femur model was extended to include a heterogeneous material description together with a strain-based criterion for crack initiation. The model was tested on two femurs, previously mechanically tested in vitro. Our results illustrate the importance of implementing a subject-specific material distribution to capture the experimental fracture pattern under stance loading. Our models accurately predicted the fracture pattern and bone strength (1% and 5% error) in both investigated femurs. This is the first study to simulate complete fracture paths in subject-specific FE femur models and it demonstrated how discrete damage models can provide a more complete picture of fracture risk by considering both bone strength and fracture toughness in a subject-specific fashion.</p>},
  author       = {Gustafsson, Anna and Tognini, Martina and Bengtsson, Frida and Gasser, T. Christian and Isaksson, Hanna and Grassi, Lorenzo},
  issn         = {1751-6161},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Journal of the Mechanical Behavior of Biomedical Materials},
  title        = {Subject-specific FE models of the human femur predict fracture path and bone strength under single-leg-stance loading},
  url          = {http://dx.doi.org/10.1016/j.jmbbm.2020.104118},
  doi          = {10.1016/j.jmbbm.2020.104118},
  volume       = {113},
  year         = {2021},
}