title: Are bi-axial proximal sesamoid bone fractures in the British Thoroughbred racehorse a bone fatigue related fracture? A histological study.
abstract: OBJECTIVE
  To investigate whether microfractures and alterations in the trabecular bone area are associated with catastrophic bi-axial proximal sesamoid bone fractures (PSBF).
  
  
  METHODS
  Proximal sesamoid bones (PSB) from 10 racehorses with PSBF and from 10 control racehorses without musculoskeletal injury were examined using the bulk basic fuchsin method. Bone histomorphometric and microfracture analysis was performed, and cases and controls compared using two-sample t-test, paired t-test, and Mann-Whitney U test.
  
  
  RESULTS
  There was no significant difference in the microfracture density and the trabecular bone area between bones from case and control horses, and between fractured and non-fractured bones in case horses.
  
  
  CONCLUSIONS
  Microfracture density was low in the areas of the PSB examined. Microfracture density was not significantly different between groups, indicating that propagation of micro-cracks is an unlikely predisposing pathologic alteration in PSBF in British racehorses. There was no significant difference in the bone surface area between groups, which one would expect if modelling, adaptation and an increase in bone density were associated with PSBF fracture in the case horses. Therefore, PSBF in the British racehorse does not appear to be associated with microfractures of the trabecular bone of the PSB. The PSB fractures might represent an acute monotonic fracture; however, the aetiology of the fractures remains unknown with additional research required.
authors.affiliation: Department of Veterinary Clinical Science, University of Liverpool, Leahurst, Neston, United Kingdom. mads.kristoffersen@djursjukhus.com
authors.forename: M
authors.initials: M
authors.lastname: Kristoffersen
authors.forename: U
authors.initials: U
authors.lastname: Hetzel
authors.forename: T D H
authors.initials: TD
authors.lastname: Parkin
authors.forename: E R
authors.initials: ER
authors.lastname: Singer
mesh_terms: D000818:Animals; D050723:Fractures, Bone / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D006734:Horse Diseases / Q000453:epidemiology / Q000473:pathology*; D006736:Horses; D012307:Risk Factors; D012716:Sesamoid Bones / Q000033:anatomy & histology / Q000293:injuries*