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Equine veterinary journal2020; 53(6); 1169-1177; doi: 10.1111/evj.13394

Microstructural properties of the proximal sesamoid bones of Thoroughbred racehorses in training.

Abstract: Proximal sesamoid bone fractures are common catastrophic injuries in racehorses. Understanding the response of proximal sesamoid bones to race training can inform fracture prevention strategies. Objective: To describe proximal sesamoid bone microstructure of racehorses and to investigate the associations between microstructure and racing histories. Methods: Cross-sectional. Methods: Proximal sesamoid bones from 63 Thoroughbred racehorses were imaged using micro-computed tomography. Bone volume fraction (BVTV) and bone material density (BMD) of the whole bone and four regions (apical, midbody dorsal, midbody palmar and basilar) were determined. Generalised linear regression models were used to identify the associations between bone parameters and race histories of the horses. Results: The mean sesamoid BVTV was 0.79 ± 0.08 and BMD was 806.02 ± 24.66 mg HA/ccm. BVTV was greater in medial sesamoids compared with lateral sesamoids (0.80 ± 0.07 vs 0.79 ± 0.08; P < .001) predominantly due to differences in the apical region (medial-0.76 ± 0.08 vs lateral-0.72 ± 0.07; P < .001). BVTV in the midbody dorsal region (0.86 ± 0.06) was greater than other regions (midbody palmar-0.79 ± 0.07, basilar-0.78 ± 0.06 and apical-0.74 ± 0.08; P < .001). BVTV was greater in sesamoids with more microcracks on their articular surface (Coef. 0.005; 95% CI 0.001, 0.009; P = .01), greater extent of bone resorption on their abaxial surface (Grade 2-0.82 ± 0.05 vs Grade 1-0.80 ± 0.05 or Grade 0-0.79 ± 0.06; P = .006), in horses with a low (0.82 ± 0.07) or mid handicap rating (0.78 ± 0.08) compared with high rating (0.76 ± 0.07; P < .001), in 2- to 5-year-old horses (0.81 ± 0.07) compared with younger (0.68 ± 0.08) or older horses (0.77 ± 0.08; P < .001) and in horses that commenced their racing career at less than 4 years of age (0.79 ± 0.08 vs 0.77 ± 0.77; P < .001). BMD was greater in the midbody dorsal (828.6 ± 19.6 mg HA/ccm) compared with other regions (apical-805.8 ± 21.8, midbody palmar-804.7 ± 18.4 and basilar-785.0 ± 17.1; P < .001), in horses with a handicap rating (low-812.1 ± 20.0, mid-821.8 ± 21.3 and high-814.6 ± 19.4) compared with those with no rating (791.08 ± 24.4, P < .001), in females (806.7 ± 22.0) and geldings (812.2 ± 22.4) compared with entires (792.7 ± 26.2; P = .02) and in older horses (<2-year-old-763.7 ± 24.8 vs 2- to 5-year-old-802.7 ± 23.4, and 6- to 12-year-old-817.8 ± 20.0; P = .002). Conclusions: Data were cross-sectional. Conclusions: Densification of the proximal sesamoid bones is associated with the commencement of racing in younger horses and the presence of bone fatigue-related pathology. Lower sesamoid BVTV was associated with longevity and better performance.
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Publication Date: 2020-12-21 PubMed ID: 33244781DOI: 10.1111/evj.13394Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper examines the microstructure of the proximal sesamoid bones in racehorses, finding that these bones’ density increases with the onset of racing in younger horses, and that lower bone volume fraction (BVTV) is tied to superior performance and longevity.

Methods

  • The researchers studied the proximal sesamoid bones of 63 Thoroughbred racehorses using micro-computed tomography (a type of x-ray imaging).
  • They assessed the bone volume fraction (BVTV) and bone material density (BMD) for the entire bone and for four regions within the bone (apical, midbody dorsal, midbody palmar, and basilar).
  • Generalised linear regression models were applied to discern any links between these bone parameters and the respective horses’ racing histories.

Results

  • The average BVTV of the sesamoid bones was 0.79, and the BMD was 806.02 mg HA/ccm.
  • The medial sesamoids had a higher BVTV than lateral ones, mainly due to differences in the apical region.
  • BVTV was greatest in the midbody dorsal region compared to other regions.
  • BMD was also found to be higher in the midbody dorsal region relative to other regions.
  • Sesamoid bones with a higher number of microcracks on their articular surface or more bone resorption on the abaxial surface had a higher BVTV.
  • Horses with low or medium handicap ratings had higher BVTV compared to those with higher ratings.
  • Horses aged 2 to 5 years had the highest BVTV compared to both older and younger horses.
  • Horses that began their racing career before the age of 4 had higher BVTV.
  • BMD was notably higher in horses with a handicap rating, in females and geldings compared to entires, and in older horses.

Conclusions

  • The proximal sesamoid bones in racehorses become denser with the start of racing at a young age, potentially indicating bone fatigue-related pathology.
  • Lower sesamoid BVTV rates were found to be associated with better performance and longevity in racehorses.
  • The findings of this study could provide useful insight towards fracture prevention strategies in racehorses.

Cite This Article

APA
Ayodele BA, Hitchens PL, Wong ASM, Mackie EJ, Whitton RC. (2020). Microstructural properties of the proximal sesamoid bones of Thoroughbred racehorses in training. Equine Vet J, 53(6), 1169-1177. https://doi.org/10.1111/evj.13394

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 6
Pages: 1169-1177

Researcher Affiliations

Ayodele, Babatunde A
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia.
Hitchens, Peta L
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia.
Wong, Adelene S M
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia.
Mackie, Eleanor J
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia.
Whitton, R Christopher
  • Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Melbourne, VIC, Australia.

MeSH Terms

  • Animals
  • Cross-Sectional Studies
  • Female
  • Fractures, Bone / diagnostic imaging
  • Fractures, Bone / veterinary
  • Horse Diseases / diagnostic imaging
  • Horses
  • Male
  • Physical Conditioning, Animal
  • Sesamoid Bones / diagnostic imaging
  • X-Ray Microtomography

Grant Funding

  • Racing Victoria Limited
  • University of Melbourne
  • Victorian Racing Industry Fund of the Victorian State Government

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Citations

This article has been cited 8 times.
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  3. Shaffer SK, Stover SM, Fyhrie DP. Training drives turnover rates in racehorse proximal sesamoid bones. Sci Rep 2023 Jan 27;13(1):205.
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