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Strain distribution in the proximal human femur during in vitro simulated sideways fall

Zani, Lorenzo; Erani, Paolo; Grassi, Lorenzo LU ; Taddei, Fulvia and Cristofolini, Luca (2015) In Journal of Biomechanics
Abstract
This study assessed: (i) how the magnitude and direction of principal strains vary for different sideways fall loading directions; (ii) how the principal strains for a sideways fall differ from physiological loading directions; (iii) the fracture mechanism during a sideways fall. Eleven human femurs were instrumented with 16 triaxial strain gauges each. The femurs were non-destructively subjected to: (a) six loading configurations covering the range of physiological loading directions; (b) twelve configurations simulating sideways falls. The femurs were eventually fractured in a sideways fall configuration while high-speed cameras recorded the event. When the same force magnitude was applied, strains were significantly larger in a sideways... (More)
This study assessed: (i) how the magnitude and direction of principal strains vary for different sideways fall loading directions; (ii) how the principal strains for a sideways fall differ from physiological loading directions; (iii) the fracture mechanism during a sideways fall. Eleven human femurs were instrumented with 16 triaxial strain gauges each. The femurs were non-destructively subjected to: (a) six loading configurations covering the range of physiological loading directions; (b) twelve configurations simulating sideways falls. The femurs were eventually fractured in a sideways fall configuration while high-speed cameras recorded the event. When the same force magnitude was applied, strains were significantly larger in a sideways fall than for physiological loading directions (principal compressive strain was 70% larger in a sideways fall). Also the compressive-to-tensile strain ratio was different: for physiological loading the largest compressive strain was only 30% larger than the largest tensile strain; but for the sideways fall, compressive strains were twice as large as the tensile strains. Principal strains during a sideways fall were nearly perpendicular to the direction of principal strains for physiological loading. In the most critical regions (medial part of the head-neck) the direction of principal strain varied by less than 9° between the different physiological loading conditions, whereas it varied by up to 17° between the sideways fall loading conditions. This was associated with a specific fracture mechanism during sideways fall, where failure initiated on the superior-lateral side (compression) followed by later failure of the medially (tension), often exhibiting a two-peak force-displacement curve. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
in press
subject
keywords
Hip fractures, Sideways fall, Physiological loading, Strain distribution, Direction of principal strain, Structural optimization
in
Journal of Biomechanics
publisher
Elsevier
external identifiers
  • scopus:84937524579
ISSN
1873-2380
DOI
10.1016/j.jbiomech.2015.02.022
language
English
LU publication?
no
id
72eb59aa-8048-4638-b515-876f7c75651b (old id 5159551)
date added to LUP
2015-03-30 12:54:22
date last changed
2017-10-22 03:21:21
@article{72eb59aa-8048-4638-b515-876f7c75651b,
  abstract     = {This study assessed: (i) how the magnitude and direction of principal strains vary for different sideways fall loading directions; (ii) how the principal strains for a sideways fall differ from physiological loading directions; (iii) the fracture mechanism during a sideways fall. Eleven human femurs were instrumented with 16 triaxial strain gauges each. The femurs were non-destructively subjected to: (a) six loading configurations covering the range of physiological loading directions; (b) twelve configurations simulating sideways falls. The femurs were eventually fractured in a sideways fall configuration while high-speed cameras recorded the event. When the same force magnitude was applied, strains were significantly larger in a sideways fall than for physiological loading directions (principal compressive strain was 70% larger in a sideways fall). Also the compressive-to-tensile strain ratio was different: for physiological loading the largest compressive strain was only 30% larger than the largest tensile strain; but for the sideways fall, compressive strains were twice as large as the tensile strains. Principal strains during a sideways fall were nearly perpendicular to the direction of principal strains for physiological loading. In the most critical regions (medial part of the head-neck) the direction of principal strain varied by less than 9° between the different physiological loading conditions, whereas it varied by up to 17° between the sideways fall loading conditions. This was associated with a specific fracture mechanism during sideways fall, where failure initiated on the superior-lateral side (compression) followed by later failure of the medially (tension), often exhibiting a two-peak force-displacement curve.},
  author       = {Zani, Lorenzo and Erani, Paolo and Grassi, Lorenzo and Taddei, Fulvia and Cristofolini, Luca},
  issn         = {1873-2380},
  keyword      = {Hip fractures,Sideways fall,Physiological loading,Strain distribution,Direction of principal strain,Structural optimization},
  language     = {eng},
  publisher    = {Elsevier},
  series       = {Journal of Biomechanics},
  title        = {Strain distribution in the proximal human femur during in vitro simulated sideways fall},
  url          = {http://dx.doi.org/10.1016/j.jbiomech.2015.02.022},
  year         = {2015},
}