Effect of Loading on the Organization of the Collagen Fibril Network in Juvenile Equine Articular Cartilage, 2009

Topics: cartilage; collagen fibril; loading; parallelism; orientation

Authors: Pieter A.J. Brama, Jaakko Holopainen, P. René van Weeren, Elwyn C. Firth, Heikki J. Helminen, Mika M. Hyttinen


We investigated the effects of exercise-induced loading on the collagen network of equine articular cartilage. Collagen fibril architecture at a site (1) subjected to intermittent high-intensity loading was compared with that of an adjacent site (2) sustaining continuous low-level load. From horses exposed to forced exercise (CONDEX group) or not (PASTEX group), the spatial parallelism of fibrils and the orientation angle between fibrils and the surface at depths 9 microm apart through cartilage from surface to tidemark were determined using polarized light microscopy, and expressed as parallelism index (PI) and orientation index (OI). PI was significantly higher in site 2 than 1 in CONDEX and PASTEX groups. PI was significantly higher in forced exercised horses at site 2 but not site 1. OI was significantly greater (more perpendicular to the surface) in the superficial and deep cartilage of site 2 than 1 in both CONDEX and PASTEX groups. Superficial zone OI was higher in exercised horses at site 1 but not at site 2. Exercise increased collagen parallelism and affected orientation. The site differences in OI indicate that Benninghoff’s classic predominantly perpendicular arcades appear not to be a consistent architectural feature, but adapt to local forces sustained.

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