University of Oulu

A. Ristaniemi, P. Tanska, L. Stenroth, M.A.J. Finnilä, R.K. Korhonen, Comparison of material models for anterior cruciate ligament in tension: from poroelastic to a novel fibril-reinforced nonlinear composite model, Journal of Biomechanics, Volume 114, 2021, 110141, ISSN 0021-9290,

Comparison of material models for anterior cruciate ligament in tension

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Author: Ristaniemi, A.1; Tanska, P.1; Stenroth, L.1;
Organizations: 1Department of Applied Physics, University of Eastern Finland, Kuopio, Finland
2Research Unit of Medical Imaging, Physics and Technology, University of Oulu, Oulu, Finland
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 4.5 MB)
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Language: English
Published: Elsevier, 2021
Publish Date: 2021-11-22


Computational models of the knee joint are useful for evaluating stresses and strains within the joint tissues. However, the outcome of those models is sensitive to the material model and material properties chosen for ligaments, the collagen reinforced tissues connecting bone to bone. The purpose of this study was to investigate different compositionally motivated material models and further to develop a model that can accurately reproduce experimentally measured stress-relaxation data of bovine anterior cruciate ligament (ACL).

Tensile testing samples were extracted from ACLs of bovine knee joints (N = 10) and subjected to a three-step stress-relaxation test at the toe region. Data from the experiments was averaged and one average finite element model was generated to replicate the experiment. Poroelastic and different fibril-reinforced poro(visco)elastic material models were applied, and their material parameters were optimized to reproduce the experimental force-time response.

Material models with only fluid flow mediated relaxation were not able to capture the stress-relaxation behavior (R² = 0.806, 0.803 and 0.938). The inclusion of the viscoelasticity of the fibrillar network improved the model prediction (R² = 0.978 and 0.976), but the complex stress-relaxation behavior was best captured by a poroelastic model with a nonlinear two-relaxation-time strain-recruited viscoelastic fibrillar network (R² = 0.997).

The results suggest that in order to replicate the multi-step stress-relaxation behavior of ACL in tension, the fibrillar network formulation should include the complex nonlinear viscoelastic phenomena.

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Series: Journal of biomechanics
ISSN: 0021-9290
ISSN-E: 1873-2380
ISSN-L: 0021-9290
Volume: 114
Article number: 110141
DOI: 10.1016/j.jbiomech.2020.110141
Type of Publication: A1 Journal article – refereed
Field of Science: 217 Medical engineering
Funding: We greatly acknowledge financial support from the Academy of Finland (grants 286526, 324529) and Sigrid Jusélius Foundation.
Copyright information: © 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license