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Home / Equine Research Bank / Equine Vet J / Subchondral bone microdamage accumulation in distal metacarp...
Equine veterinary journal2018; 50(6); 766-773; doi: 10.1111/evj.12948

Subchondral bone microdamage accumulation in distal metacarpus of Thoroughbred racehorses.

Abstract: Microdamage accumulation leads to subchondral bone injury and/or fracture in racehorses. An understanding of this process is essential for developing strategies for injury prevention. Objective: To quantify subchondral bone microdamage in the third metacarpal bone of Thoroughbred racehorses at different stages of the training cycle. Methods: Cross-sectional. Methods: Bone blocks from the palmar aspect of the medial condyles of third metacarpal bones from 46 racing Thoroughbred horses undergoing post-mortem were examined with micro computed tomography (microCT) to detect calcified microcracks, and light microscopy to quantify bulk stained microcracks. Racing and training histories were obtained for comparison with microdamage data using regression modelling. Results: Subchondral bone microcracks were observed in all bones with at least one method. Microdamage grade was greater in older horses, levelling-off for horses 5 years and older (quadratic term P = 0.01), and with lower bone material density in the parasagittal groove (P = 0.02). Microcrack density was higher in older horses (P = 0.004), and with higher bone volume fraction (BV/TV) in the parasagittal groove in horses in training (interaction effect, P = 0.01) and lower in horses resting from training (P = 0.02). Conclusions: Cross-sectional data only. Incomplete detection of microdamage due to the limits of resolution of microCT and lack of three-dimensional imaging with microscopy. Multicollinearity between variables that indicated career progression (e.g. age, number of career starts, duration of training period) was detected. Conclusions: Fatigue damage in the distal metacarpal subchondral bone is common in Thoroughbred racehorses undergoing post-mortem and appears to accumulate throughout a racing career. Reduced intensity or duration of training and racing and/or increased duration of rest periods may limit microdamage accumulation. Focal subchondral bone sclerosis indicates the presence of microdamage.
© 2018 EVJ Ltd.
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Publication Date: 2018-05-12 PubMed ID: 29660153DOI: 10.1111/evj.12948Google Scholar: Lookup
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Summary

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The research investigates how microdamage builds up in the subchondral bone of the third metacarpal in Thoroughbred racehorses. It finds that this microdamage is common in these horses and increases throughout their racing careers, with potential implications for injury prevention and training strategies.

Study Objective and Methodology

  • The study aimed to quantify subchondral (below the cartilage) bone microdamage in the third metacarpal bone of Thoroughbred racehorses at various stages of their training cycle. The increase in such damage can lead to serious injuries and fractures.
  • Bone samples were collected from 46 Thoroughbred horses that had been racing, after their death. These samples were taken from the palmar aspect of the medial condyles of the third metacarpal bones.
  • Microcomputed tomography (microCT) was used to detect calcified microcracks, whereas light microscopy was employed to quantify bulk stained microcracks.
  • The researchers obtained the racing and training histories of these horses for comparison with the microdamage data, employing regression modelling for this purpose.

Key Findings

  • Microcracks in the subchondral bone were found in all samples to some extent.
  • The degree of microdamage was greater in older horses, leveling off for horses aged 5 years and above.
  • Microcrack density was higher in older horses, and in those with a higher bone volume fraction in the parasagittal groove during training.
  • Among horses resting from training, lower microcrack density was observed.

Implications and Conclusion

  • Microdamage accumulation is common in Thoroughbred racehorses, increasing throughout their racing career. Reducing the intensity or duration of training/racing, or increasing the duration of resting periods might help limit this accumulation.
  • One of the key indications of the presence of microdamage was focal subchondral bone sclerosis.
  • The study’s conclusions are based only on cross-sectional data. The detection of microdamage was incomplete due to the limits of resolution of the used techniques (microCT and microscopy) and the absence of three-dimensional imaging.
  • The researchers noted multicollinearity between variables pointing to career progression, such as age, number of career starts, and duration of the training period.

Cite This Article

APA
Whitton RC, Ayodele BA, Hitchens PL, Mackie EJ. (2018). Subchondral bone microdamage accumulation in distal metacarpus of Thoroughbred racehorses. Equine Vet J, 50(6), 766-773. https://doi.org/10.1111/evj.12948

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 50
Issue: 6
Pages: 766-773

Researcher Affiliations

Whitton, R C
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia.
Ayodele, B A
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia.
Hitchens, P L
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia.
Mackie, E J
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, Australia.

MeSH Terms

  • Age Factors
  • Animals
  • Calcinosis / diagnostic imaging
  • Calcinosis / veterinary
  • Coloring Agents
  • Cross-Sectional Studies
  • Female
  • Horses / classification
  • Horses / injuries
  • Linear Models
  • Logistic Models
  • Male
  • Metacarpus / diagnostic imaging
  • Metacarpus / injuries
  • Physical Conditioning, Animal
  • Rosaniline Dyes
  • Staining and Labeling / methods
  • Staining and Labeling / veterinary
  • X-Ray Microtomography / veterinary

Grant Funding

  • Racing Victoria Limited
  • Victorian State Government

Citations

This article has been cited 28 times.
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