title: Relationship between cartilage and subchondral bone lesions in repetitive impact trauma-induced equine osteoarthritis.
abstract: OBJECTIVE
  To correlate degenerative changes in cartilage and subchondral bone in the third carpal bone (C3) of Standardbred racehorses with naturally occurring repetitive trauma-induced osteoarthritis.
  
  
  METHODS
  Fifteen C3, collected from Standardbred horses postmortem, were assessed for cartilage lesions by visual inspection and divided into Control (CO), Early Osteoarthritis (EOA) and Advanced Osteoarthritis (AOA) groups. Two osteochondral cores were harvested from corresponding dorsal sites on each bone and scanned with a micro-computed tomography (CT) instrument. 2D images were assembled into 3D reconstructions that were used to quantify architectural parameters from selected regions of interest, including bone mineral density and bone volume fraction. 2D images, illustrating the most severe lesion per core, were scored for architectural appearance by blinded observers. Thin sections of paraffin-embedded decalcified cores stained with Safranin O-Fast Green, matched to the micro-CT images, were scored using a modified Mankin scoring system.
  
  
  RESULTS
  Subchondral bone pits with deep focal areas of porosity were seen more frequently in AOA than EOA but never in CO. Articular cartilage damage was seen in association with a reduction in bone mineral and loss of bone tissue. Histological analyses revealed significant numbers of microcracks in the calcified cartilage of EOA and AOA groups and a progressive increase in the score compared with CO bones.
  
  
  CONCLUSIONS
  The data reveal corresponding, progressive degenerative changes in articular cartilage and subchondral bone, including striking focal resorptive lesions, in the third carpal bone of racehorses subjected to repetitive, high impact trauma.
authors.affiliation: Comparative Orthopaedic Research Laboratory, Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, C.P. 5000, Saint-Hyacinthe (QC), J2S 7C6, Canada. MatLacourt@aol.com
authors.forename: M
authors.initials: M
authors.lastname: Lacourt
authors.forename: C
authors.initials: C
authors.lastname: Gao
authors.forename: A
authors.initials: A
authors.lastname: Li
authors.forename: C
authors.initials: C
authors.lastname: Girard
authors.forename: G
authors.initials: G
authors.lastname: Beauchamp
authors.forename: J E
authors.initials: JE
authors.lastname: Henderson
authors.forename: S
authors.initials: S
authors.lastname: Laverty
mesh_terms: D000818:Animals; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000473:pathology; D002350:Carpus, Animal / Q000000981:diagnostic imaging / Q000473:pathology*; D002357:Cartilage Diseases / Q000000981:diagnostic imaging / Q000473:pathology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology*; D012090:Cumulative Trauma Disorders / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D018450:Disease Progression; D005260:Female; D006734:Horse Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D006736:Horses; D008297:Male; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000473:pathology / Q000662:veterinary*; D016062:Porosity; D055114:X-Ray Microtomography / Q000379:methods