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On the internal reaction forces, energy absorption, and fracture in the hip during simulated sideways fall impact

On the internal reaction forces, energy absorption, and fracture in the hip during simulated sideways fall impact

Title: On the internal reaction forces, energy absorption, and fracture in the hip during simulated sideways fall impact
Author: Fleps, Ingmar
Enns-Bray, William S.
Guy, Pierre
Ferguson, Stephen J.
Cripton, Peter A.
Helgason, Benedikt
Date: 2018-11-26
Language: English
Scope: e0208286
University/Institute: Háskólinn í Reykjavík
Reykjavik University
School: Tækni- og verkfræðideild (HR)
School of Science and Engineering (RU)
Series: PLOS ONE;13(11)
ISSN: 1932-6203
DOI: 10.1371/journal.pone.0200952
Subject: Soft-tissue thickness; Finite-element models; Proximal femur; Femoral-neck; Prediction; Bone; Risk; Load; Subject; Spine; Mjaðmarbrot; Beinbrot; Útlimir; Byltur; Bútaaðferð
URI: https://hdl.handle.net/20.500.11815/1419

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FlepsI, Enns-BrayWS, Guy P, FergusonSJ, CriptonPA, HelgasonB (2018)On the internalreactionforces,energyabsorption,and fractureinthe hip duringsimulatedsidewaysfall impact.PLoSONE 13(8):e0200952.https://doi.org/10.1371/journal.pone.0200952


The majority of hip fractures have been reported to occur as a result of a fall with impact to the greater trochanter of the femur. Recently, we developed a novel cadaveric pendulum-based hip impact model and tested two cadaveric femur-pelvis constructs, embedded in a soft tissue surrogate. The outcome was a femoral neck fracture in a male specimen while a female specimen had no fracture. The aim of the present study was, first, to develop a methodology for constructing and assessing the accuracy of explicit Finite Element Models (FEMs) for simulation of sideways falls to the hip based on the experimental model. Second, to use the FEMs for quantifying the internal reaction forces and energy absorption in the hip during impact. Third, to assess the potential of the FEMs in terms of separating a femoral fracture endpoint from a non-fracture endpoint. Using a non-linear, strain rate dependent, and heterogeneous material mapping strategy for bone tissue in these models, we found the FEM-derived results to closely match the experimental test results in terms of impact forces and displacements of pelvic video markers up to the time of peak impact force with errors below 10%. We found the internal reaction forces in the femoral neck on the impact side to be approximately 35% lower than the impact force measured between soft tissue and ground for both specimens. In addition, we found the soft tissue to be the component that absorbed the largest part of the energy of the tissue types in the hip region. Finally, we found surface strain patterns derived from FEM results to match the fracture location and extent based on post testing x-rays of the specimens. This is the first study with quantitative data on the energy absorption in the pelvic region during a sideways fall.


All result files and supplementary videos are available through the ETH Research Collection (DOI:10.3929/ethz-b-000238902).


This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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