title: Effect of loading on the organization of the collagen fibril network in juvenile equine articular cartilage.
abstract: 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.
authors.affiliation: School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland. pieter.brama@ucd.ie
authors.forename: Pieter A J
authors.initials: PA
authors.lastname: Brama
authors.forename: Jaakko
authors.initials: J
authors.lastname: Holopainen
authors.forename: P René
authors.initials: PR
authors.lastname: van Weeren
authors.forename: Elwyn C
authors.initials: EC
authors.lastname: Firth
authors.forename: Heikki J
authors.initials: HJ
authors.lastname: Helminen
authors.forename: Mika M
authors.initials: MM
authors.lastname: Hyttinen
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002358:Cartilage, Articular / Q000293:injuries* / Q000473:pathology / Q000502:physiology*; D003094:Collagen / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D005260:Female; D005552:Forelimb; D006734:Horse Diseases / Q000473:pathology / Q000503:physiopathology*; D006736:Horses; D008297:Male; D008859:Microscopy, Polarization; D010805:Physical Conditioning, Animal / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*
chemical_list: D003094:Collagen