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Author Affolter, C.; Kedzierska, J.; Vielma, T.; Weisse, B.; Aiyangar, A. doi  openurl
  Title Estimating lumbar passive stiffness behaviour from subject-specific finite element models and in vivo 6DOF kinematics Type
  Year 2020 Publication Journal Of Biomechanics Abbreviated Journal J. Biomech.  
  Volume 102 Issue Pages 11 pp  
  Keywords Lumbar spinal loading; Subject-specific kinematics; Passive stiffness; Neutral position; Rigid-body musculoskeletal modelling  
  Abstract Passive rotational stiffness of the osseo-ligamentous spine is an important input parameter for estimating in-vivo spinal loading using musculoskeletal models. These data are typically acquired from cadaveric testing. Increasingly, they are also estimated from subject-specific imaging-based finite element (FE) models, which are typically built from CT/MR data obtained in supine position and employ pure rotation kinematics. We explored the sensitivity of FE-based lumbar passive rotational stiffness to two aspects of functional in-vivo kinematics: (a) passive strain changes from supine to upright standing position, and (b) in-vivo coupled translation-rotation kinematics. We developed subject-specific FE models of four subjects' L4L5 segments from supine CT images. Sagittally symmetric flexion was simulated in two ways: (i) pure flexion up to 12 degrees under a 500 N follower load directly from the supine pose. (ii) First, a displacement-based approach was implemented to attain the upright pose, as measured using Dynamic Stereo X-ray (DSX) imaging. We then simulated in-vivo flexion using DSX imaging-derived kinematics. Datasets from weight-bearing motion with three different external weights [(4.5 kg), (9.1 kg), (13.6 kg)] were used. Accounting for supine-upright motion generated compressive pre-loads approximate to 468 N (+/- 188 N) and a “pre-torque” approximate to 2.5 Nm (+/- 2.2 Nm), corresponding to 25% of the reaction moment at 10 degrees flexion (case (i)). Rotational stiffness estimates from DSX-based coupled translation-rotation kinematics were substantially higher compared to pure flexion. Reaction Moments were almost 90% and 60% higher at 5 degrees and 10 degrees of L4L5 flexion, respectively. Within-subject differences in rotational stiffness based on external weight were small, although between-subject variations were large. (C) 2020 Elsevier Ltd. All rights reserved.  
  Address [Affolter, Christian; Weisse, Bernhard; Aiyangar, Ameet] EMPA Swiss Fed Labs Mat Sci & Technol, Mech Syst Engn, Dubendorf, Switzerland, Email:  
  Corporate Author Thesis  
  Publisher Elsevier Sci Ltd Place of Publication Editor  
  Language English Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0021-9290 ISBN Medium  
  Area Expedition Conference  
  Notes WOS:000528310700033 Approved  
  Call Number UAI @ eduardo.moreno @ Serial 1142  
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