University of Oulu

Ebrahimi, M., Turkiewicz, A., Finnilä, M. A. J., Saarakkala, S., Englund, M., Korhonen, R. K., & Tanska, P. (2022). Associations of human femoral condyle cartilage structure and composition with viscoelastic and constituent-specific material properties at different stages of osteoarthritis. Journal of Biomechanics, 145, 111390.

Associations of human femoral condyle cartilage structure and composition with viscoelastic and constituent-specific material properties at different stages of osteoarthritis

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Author: Ebrahimi, Mohammadhossein1,2; Turkiewicz, Aleksandra3; Finnilä, Mikko A.J.2;
Organizations: 1Department of Technical Physics, University of Eastern Finland, Kuopio, Finland
2Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland
3Faculty of Medicine, Department of Clinical Sciences Lund, Orthopaedics, Clinical Epidemiology Unit, Lund University, Lund, Sweden
4Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 5.1 MB)
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Language: English
Published: Elsevier, 2022
Publish Date: 2023-06-02


The relationships between structure and function in human knee femoral cartilage are not well-known at different stages of osteoarthritis. Thus, our aim was to characterize the depth-dependent composition and structure (proteoglycan content, collagen network organization and collagen content) of normal and osteoarthritic human femoral condyle cartilage (n = 47) and relate them to their viscoelastic and constituent-specific mechanical properties that are obtained through dynamic sinusoidal testing and fibril-reinforced poroelastic material modeling of stress-relaxation testing, respectively. We characterized the proteoglycan content using digital densitometry, collagen network organization (orientation angle and anisotropy) using polarized light microscopy and collagen content using Fourier transform infrared spectroscopy. In the superficial cartilage (0–10 % of thickness), the collagen network disorganization and proteoglycan loss were associated with the smaller initial fibril network modulus — a parameter representing the pretension of the collagen network. Furthermore, the proteoglycan loss was associated with the greater strain-dependent fibril network modulus — a measure of nonlinear mechanical behavior. The proteoglycan loss was also associated with greater cartilage viscosity at a low loading frequency (0.005 Hz), while the collagen network disorganization was associated with greater cartilage viscosity at a high loading frequency (1 Hz). Our results suggest that proteoglycan loss and collagen network disorganization reduce the pretension of the collagen network while proteoglycan degradation also increases the nonlinear mechanical behavior of the collagen network. Further, the results also highlight that proteoglycan loss and collagen disorganization increase the viscosity of femoral cartilage, but their contribution to increased viscosity occurs in completely different loading frequencies.

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Series: Journal of biomechanics
ISSN: 0021-9290
ISSN-E: 1873-2380
ISSN-L: 0021-9290
Volume: 145
Article number: 111390
DOI: 10.1016/j.jbiomech.2022.111390
Type of Publication: A1 Journal article – refereed
Field of Science: 3126 Surgery, anesthesiology, intensive care, radiology
3111 Biomedicine
217 Medical engineering
318 Medical biotechnology
Funding: This work was supported by the Academy of Finland (grants 324529 and 268378); strategic funding of the University of Eastern Finland; Maire Lisko Foundation; Finnish Cultural Foundation, North Savo Regional Fund (grant 65191841); Emil Aaltonen Foundation (grant 200016); Alfred Kordelin Foundation (grant 190111); and Sigrid Juse- lius Foundation. The study (MENIX biobank) and contributions by M Englund and A Turkiewicz are supported by the Swedish Research Council, The Swedish Rheumatology Association, ̈Osterlund Foundation and Governmental funding of clinical research within the national health services (ALF).
Academy of Finland Grant Number: 268378
Detailed Information: 268378 (Academy of Finland Funding decision)
Copyright information: © 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (