title: Biochemical analysis of the articular cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis.
abstract: OBJECTIVE
  To assess whether site-related changes in biochemical composition are present in the cartilage and subchondral and trabecular bone of the metacarpophalangeal joint of horses with early osteoarthritis.
  
  
  METHODS
  Right metacarpophalangeal joints from 59 mature warmblood horses.
  
  
  METHODS
  Biochemical data (cross-link, amino acid, DNA, and ash contents; denatured collagen and glycosaminoglycan [GAG] concentrations; bone mineral density; and mineral composition) were obtained from 2 differently loaded sites of phalanx I cartilage and subchondral and trabecular bone samples; data were compared with previously published values from nonosteoarthritic equine joints.
  
  
  RESULTS
  Compared with findings in nonosteoarthritic joints, GAG concentration was lower in cartilage from osteoarthritic joints and there was a loss of site differences in cellularity and lysylpyridinoline (LP) cross-link content. In subchondral bone, LP cross-link content was decreased overall and there was a loss of site differences in osteoarthritic joints; ash content was higher in the osteoarthritic joints. Hydroxyproline content in trabecular bone from osteoarthritic joints was greater than that in nonosteoarthritic trabecular bone. In all 3 layers and at both sites, the linear increase of the pentosidine cross-link content with age had diminished or was not apparent in the horses with osteoarthritic joints.
  
  
  CONCLUSIONS
  In equine metacarpophalangeal joints with early osteoarthritis, distinct biochemical changes were detected in the cartilage and subchondral and trabecular bone. The dissimilarity in response of the different tissues and differences between the sites that are affected may be related to differences in biomechanical loading and transmission and dissipation of force.
authors.affiliation: Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Yalelaan 12, 3584 CM Utrecht, The Netherlands.
authors.forename: Mark R
authors.initials: MR
authors.lastname: van der Harst
authors.forename: Jeroen
authors.initials: J
authors.lastname: DeGroot
authors.forename: Geesje H
authors.initials: GH
authors.lastname: Kiers
authors.forename: Pieter A J
authors.initials: PA
authors.lastname: Brama
authors.forename: Chris H A
authors.initials: CH
authors.lastname: van de Lest
authors.forename: P René
authors.initials: PR
authors.lastname: van Weeren
mesh_terms: D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism* / Q000473:pathology; D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology; D005552:Forelimb; D006025:Glycosaminoglycans / Q000502:physiology; D006734:Horse Diseases / Q000378:metabolism* / Q000473:pathology; D006736:Horses; D010003:Osteoarthritis / Q000503:physiopathology / Q000662:veterinary*
chemical_list: D006025:Glycosaminoglycans