| Autor: |
Ebrahimi M; Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland. mohammadhossein.ebrahimi@uef.fi.; Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland. mohammadhossein.ebrahimi@uef.fi., Turunen MJ; Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland.; SIBlabs, University of Eastern Finland, Kuopio, Finland., Finnilä MA; Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland., Joukainen A; Kuopio University Hospital, Kuopio, Finland., Kröger H; Kuopio University Hospital, Kuopio, Finland., Saarakkala S; Research Unit of Medical Imaging, Physics and Technology, Faculty of Medicine, University of Oulu, Oulu, Finland.; Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland., Korhonen RK; Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland., Tanska P; Department of Applied Physics, University of Eastern Finland, POB 1627, 70211, Kuopio, Finland. |
| Abstrakt: |
Relationships between composition, structure and constituent-specific functional properties of human articular cartilage at different stages of osteoarthritis (OA) are poorly known. We established these relationships by comparison of elastic, viscoelastic and fibril-reinforced poroelastic mechanical properties with microscopic and spectroscopic analysis of structure and composition of healthy and osteoarthritic human tibial cartilage (n = 27). At a low frequency (0.005 Hz), proteoglycan content correlated negatively and collagen content correlated positively with the phase difference (i.e. tissue viscosity). At a high-frequency regime (> 0.05 Hz), proteoglycan content correlated negatively and collagen orientation angle correlated positively with the phase difference. Proteoglycans were lost in the early and advanced OA groups compared to the healthy group, while the superficial collagen orientation angle was greater only in the advanced OA group compared to the healthy group. Simultaneously, the initial fibril network modulus (fibril pretension) was smaller in the early and advanced OA groups compared to the healthy group. These findings suggest different mechanisms contribute to cartilage viscosity in low and high frequencies, and that the loss of superficial collagen pretension during early OA is due to lower tissue swelling (PG loss), while in advanced OA, both collagen disorganization and lower swelling modulate the collagen fibril pretension. |
Full text from SpringerLink