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Author  |
Affolter, C.; Kedzierska, J.; Vielma, T.; Weisse, B.; Aiyangar, A. |
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Title |
Estimating lumbar passive stiffness behaviour from subject-specific finite element models and in vivo 6DOF kinematics |
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Year |
2020 |
Publication |
Journal Of Biomechanics |
Abbreviated Journal |
J. Biomech. |
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Volume |
102 |
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11 pp |
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Keywords |
Lumbar spinal loading; Subject-specific kinematics; Passive stiffness; Neutral position; Rigid-body musculoskeletal modelling |
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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. |
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Address |
[Affolter, Christian; Weisse, Bernhard; Aiyangar, Ameet] EMPA Swiss Fed Labs Mat Sci & Technol, Mech Syst Engn, Dubendorf, Switzerland, Email: ameet.aiyangar@empa.ch |
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Elsevier Sci Ltd |
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English |
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0021-9290 |
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WOS:000528310700033 |
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UAI @ eduardo.moreno @ |
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1142 |
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