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

Research output: Contribution to journalArticle

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 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.

Details

Authors
Organisations
External organisations
  • KTH Royal Institute of Technology
  • Lund University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medical Materials

Keywords

  • Cohesive traction separation law, Crack propagation, Crack surface, Partition of unity, PUFEM, XFEM
Original languageEnglish
Article number104118
JournalJournal of the Mechanical Behavior of Biomedical Materials
Volume113
Publication statusPublished - 2021
Publication categoryResearch
Peer-reviewedYes