title: Can we use subchondral bone thickness on high-field magnetic resonance images to identify Thoroughbred racehorses at risk of catastrophic lateral condylar fracture?
abstract: BACKGROUND
  Fractures of the lateral condyle of the third metacarpus (MC3) are a significant welfare concern in horseracing worldwide.
  
  
  OBJECTIVE
  The primary aim of this work was to identify magnetic resonance (MR) image-detectable prefracture markers that have the potential for use as a screening tool to identify horses at significant risk of catastrophic fracture.
  
  
  METHODS
  Case-control study of bone-level risk factors for fracture in racehorses.
  
  
  METHODS
  A total of 191 MC3s from horses, with and without lateral condylar fracture of MC3, were subjected to MR imaging. The depth of dense subchondral/trabecular bone was measured at several sites around the distal end of the bone and regression analyses were conducted to identify differences in this depth between horses with and without lateral condylar fracture.
  
  
  RESULTS
  Greater depth of dense subchondral/trabecular bone in the palmar half of the lateral parasagittal groove of distal MC3 was associated with an increased likelihood of being from a horse that had sustained a fracture. Receiver operator characteristic analysis was used to identify the optimal cut-off in the depth of dense subchondral/trabecular bone at this site to best discriminate fracture status. Positive and negative predictive values were calculated using the prevalence of fracture within the current study and also a prevalence estimate for the wider racehorse population.
  
  
  CONCLUSIONS
  There is a requirement to identify suitable prescreening test(s) to eliminate many true negative horses and increase the prevalence of prefracture pathology in the sub population that would be screened using MR imaging, in turn maximising the positive predictive value of this test.
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK.
authors.forename: C A
authors.initials: CA
authors.lastname: Tranquille
authors.affiliation: Centre for Equine Studies, Animal Health Trust, Newmarket, Suffolk, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Murray
authors.affiliation: School of Veterinary Medicine, College of Medical, Veterinary and Life Sciences, Weiper's Centre Equine Hospital, University of Glasgow, Glasgow, UK.
authors.forename: T D H
authors.initials: TD
authors.lastname: Parkin
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D015519:Bone Density / Q000502:physiology*; D001842:Bone and Bones / Q000502:physiology; D016022:Case-Control Studies; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000662:veterinary*; D006734:Horse Diseases / Q000000981:diagnostic imaging*; D006736:Horses / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000662:veterinary*; D050279:Metacarpal Bones / Q000473:pathology*; D011237:Predictive Value of Tests
keywords: fracture prevention; magnetic resonance imaging; racehorse; screening; subchondral bone thickness