title: Detection of early osteoarthritis in the centrodistal joints of Icelandic horses: Evaluation of radiography and low-field magnetic resonance imaging.
abstract: BACKGROUND
  Validated noninvasive detection methods for early osteoarthritis (OA) are required for OA prevention and early intervention treatment strategies.
  
  
  OBJECTIVE
  To evaluate radiography and low-field magnetic resonance imaging (MRI) for the detection of early stage OA osteochondral lesions in equine centrodistal joints using microscopy as the reference standard.
  
  
  METHODS
  Prospective imaging of live horses and imaging and microscopy of cadaver tarsal joints.
  
  
  METHODS
  Centrodistal (distal intertarsal) joints of 38 Icelandic research horses aged 27-29 months were radiographed. Horses were subjected to euthanasia approximately 2 months later and cadaver joints examined with low-field MRI. Osteochondral joint specimens were classified as negative or positive for OA using light microscopy histology or scanning electron microscopy. Radiographs and MRIs were evaluated for osteochondral lesions and results compared with microscopy.
  
  
  RESULTS
  Forty-two joints were classified OA positive with microscopy. Associations were detected between microscopic OA and the radiography lesion categories; mineralisation front defect (P<0.0001), joint margin lesion (P<0.0001), central osteophyte (P = 0.03) and the low-field MRI lesion categories; mineralisation front defect (P = 0.01), joint margin lesion (P = 0.02) and articular cartilage lesion (P = 0.0003). The most frequent lesion category detected in microscopic OA positive joints was the mineralisation front defect in radiographs (28/42 OA positive joints, specificity 97%, sensitivity 67%). No significant differences were detected between the sensitivity and specificity of radiography and low-field MRI pooled lesion categories, but radiography was often superior when individual lesion categories were compared.
  
  
  CONCLUSIONS
  Early stage centrodistal joint OA changes may be detected with radiography and low-field MRI. Detection of mineralisation front defects in radiographs may be a useful screening method for detection of early OA in centrodistal joints of young Icelandic horses.
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: C J
authors.initials: CJ
authors.lastname: Ley
authors.affiliation: Icelandic Food and Veterinary Authority, Selfoss, Iceland.
authors.forename: S
authors.initials: S
authors.lastname: Björnsdóttir
authors.affiliation: Department of Biomedical Sciences and Veterinary Public Health, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Ekman
authors.affiliation: Biophysics, Oral Growth and Development, Dental Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Boyde
authors.affiliation: Department of Clinical Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Hansson
mesh_terms: D000818:Animals; D002102:Cadaver; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging; D006736:Horses; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000662:veterinary*; D008297:Male; D010003:Osteoarthritis / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000662:veterinary*; D011859:Radiography; D013643:Tarsus, Animal / Q000000981:diagnostic imaging / Q000473:pathology
keywords: bone spavin; degenerative joint disease; histology; horse; scanning electron microscopy; tarsus; validation