title: Effects of exercise vs experimental osteoarthritis on imaging outcomes.
abstract: OBJECTIVE
  To identify changes in imaging outcomes in a controlled model of osteoarthritis (OA) vs exercise.
  
  
  METHODS
  Sixteen 2-year-old horses were randomly assigned to an exercise control (n=8) or an exercise OA (n=8) group. All horses had middle carpal joints arthroscopically explored and an osteochondral fragment was induced in one middle carpal joint of the OA group. All horses were treadmill exercised for the duration of the study (91 days). Clinical, radiographic, nuclear scintigraphic, computed tomographic and magnetic resonance imaging (MRI) examinations were performed and outcomes of these were compared between groups. Imaging results were correlated to clinical, biomarker and gross pathologic results.
  
  
  RESULTS
  The OA group had significant increases in clinical outcomes and most imaging parameters. Specifically, the OA group showed significant increases in radiographic lysis and nuclear scintigraphic uptake. There was very little change in subchondral bone density, but a significant change in subchondral bone edema. Radiographic lysis, radial carpal bone edema and nuclear scintigraphy were strongly correlated with clinical changes and radial carpal bone edema was strongly correlated with changes in Type I and Type II collagen found in the synovial fluid.
  
  
  CONCLUSIONS
  OA induced significant changes in imaging parameters beyond the adaptation seen with exercise. Bone edema detected with MRI was closely correlated with collagen biomarkers detected in the synovial fluid.
authors.affiliation: Department of Clinical Sciences, Equine Orthopaedic Research Center, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States. ckawcak@colostate.edu
authors.forename: C E
authors.initials: CE
authors.lastname: Kawcak
authors.forename: D D
authors.initials: DD
authors.lastname: Frisbie
authors.forename: N M
authors.initials: NM
authors.lastname: Werpy
authors.forename: R D
authors.initials: RD
authors.lastname: Park
authors.forename: C W
authors.initials: CW
authors.lastname: McIlwraith
mesh_terms: D000818:Animals; D002350:Carpus, Animal / Q000378:metabolism / Q000473:pathology*; D002358:Cartilage, Articular / Q000473:pathology*; D003952:Diagnostic Imaging; D018450:Disease Progression; D006734:Horse Diseases / Q000175:diagnosis*; D006736:Horses; D007794:Lameness, Animal / Q000175:diagnosis*; D010003:Osteoarthritis / Q000473:pathology* / Q000662:veterinary; D010805:Physical Conditioning, Animal / Q000502:physiology*; D011897:Random Allocation