title: Evaluation of experimental impact injury for inducing post-traumatic osteoarthritis in the metacarpophalangeal joints of horses.
abstract: OBJECTIVE
  To determine whether a single contusive impact injury to the palmar aspect of the metacarpus would progress to post-traumatic osteoarthritis or palmar osteochondral disease in horses.
  
  
  METHODS
  12 horses.
  
  
  METHODS
  In each horse, an impact injury was created on the palmar aspect of the medial metacarpal condyle of 1 randomly chosen limb with an impactor device under arthroscopic and fluoroscopic guidance. The opposite limb was sham operated as a control. A low to moderate amount of forced exercise was instituted, and horses were evaluated clinically via lameness examinations weekly for 5 months, then biweekly until endpoint, with synovial fluid analysis performed at 0, 1, 2, 3, 4, 6, 8, and 10 months and radiography at baseline and endpoint. Macroscopic examination, micro-CT, and sample collection for cartilage viability and sulfated glycosaminoglycan content, histologic evaluation, immunohistochemical analysis, and fluorochrome analysis were performed following euthanasia at 1 (3 horses), 4 (4), and 8 to 10 (5) months after surgery.
  
  
  RESULTS
  There was variability in impact lesion location, depth, and area on macroscopic inspection, but on histologic evaluation, cartilage defects were less variable. Mean sulfated glycosaminoglycan concentration from cartilage at the impact site was significantly lower than that at a similar site in control limbs. Higher concentrations of cartilage oligomeric matrix protein were observed in synovial fluid from impact-injured joints.
  
  
  CONCLUSIONS
  The impact injury method caused mild focal osteoarthritic lesions in the metacarpophalangeal joint, but did not progress to palmar osteochondral disease at this site. Repeated injury is probably required for the development of palmar osteochondral disease.
authors.affiliation: Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada. ellen.rickey@gmail.com
authors.forename: Ellen J
authors.initials: EJ
authors.lastname: Rickey
authors.forename: Antonio M
authors.initials: AM
authors.lastname: Cruz
authors.forename: Donald R
authors.initials: DR
authors.lastname: Trout
authors.forename: Beverly J
authors.initials: BJ
authors.lastname: McEwen
authors.forename: Mark B
authors.initials: MB
authors.lastname: Hurtig
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000378:metabolism / Q000473:pathology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D005528:Foot / Q000473:pathology*; D005552:Forelimb / Q000378:metabolism / Q000473:pathology; D006023:Glycoproteins / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D006734:Horse Diseases / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D006736:Horses; D007596:Joints / Q000378:metabolism / Q000473:pathology*; D064235:Matrilin Proteins; D010003:Osteoarthritis / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D055034:Osteochondrosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology / Q000662:veterinary*; D013582:Synovial Fluid / Q000378:metabolism; D013997:Time Factors
chemical_list: D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006025:Glycosaminoglycans; D064235:Matrilin Proteins; C013786:A73025