Effect of superficial collagen patterns and fibrillation of femoral articular cartilage on knee joint mechanics—A 3D finite element analysis

Mononen, M.E.; Mikkola, M.T.; Julkunen, P.; Ojala, R.; Nieminen, M.T.; Jurvelin, J.S.; Korhonen, R.K.

doi:10.1016/j.jbiomech.2011.11.003

« Previous Next »Journal of Biomechanics
Volume 45, Issue 3 , Pages 579-587, 2 February 2012

Effect of superficial collagen patterns and fibrillation of femoral articular cartilage on knee joint mechanics—A 3D finite element analysis

M.E. Mononen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland
- Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital, Kuopio, Finland
- Corresponding author at: Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland. Tel.: +358 40 3553260; fax: +358 17 163266.
M.T. Mikkola
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland
P. Julkunen
- Department of Clinical Neurophysiology, Kuopio University Hospital, Kuopio, Finland
R. Ojala
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
M.T. Nieminen
- Department of Diagnostic Radiology, Oulu University Hospital, Oulu, Finland
- Department of Medical Technology, University of Oulu, Oulu, Finland
J.S. Jurvelin
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland
R.K. Korhonen
- Department of Applied Physics, University of Eastern Finland, POB 1627, FI-70211 Kuopio, Finland

Accepted 6 November 2011. published online 02 December 2011.

Abstract

Collagen fibrils of articular cartilage have specific depth-dependent orientations and the fibrils bend in the cartilage surface to exhibit split-lines. Fibrillation of superficial collagen takes place in osteoarthritis. We aimed to investigate the effect of superficial collagen fibril patterns and collagen fibrillation of cartilage on stresses and strains within a knee joint.

A 3D finite element model of a knee joint with cartilage and menisci was constructed based on magnetic resonance imaging. The fibril-reinforced poroviscoelastic material properties with depth-dependent collagen orientations and split-line patterns were included in the model. The effects of joint loading on stresses and strains in cartilage with various split-line patterns and medial collagen fibrillation were simulated under axial impact loading of 1000N.

In the model, the collagen fibrils resisted strains along the split-line directions. This increased also stresses along the split-lines. On the contrary, contact and pore pressures were not affected by split-line patterns. Simulated medial osteoarthritis increased tissue strains in both medial and lateral femoral condyles, and contact and pore pressures in the lateral femoral condyle.

This study highlights the importance of the collagen fibril organization, especially that indicated by split-line patterns, for the weight-bearing properties of articular cartilage. Osteoarthritic changes of cartilage in the medial femoral condyle created a possible failure point in the lateral femoral condyle. This study provides further evidence on the importance of the collagen fibril organization for the optimal function of articular cartilage.

Keywords: Articular cartilage, Split-line pattern, Osteoarthritis, Magnetic resonance imaging, Finite element analysis