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Equine veterinary journal2025; doi: 10.1111/evj.70102

Retrospective performance-indexed analysis of Thoroughbred racehorses undergoing surgical management of proximal sesamoid bone fractures.

Abstract: Proximal sesamoid bone fractures (PSBFs) are a leading cause of economic losses. Post-operative racing prognosis is multi-factorial; however, recent studies are lacking. Objective: To provide an update on racing outcomes for horses undergoing surgical management of PSBFs, analyse variables affecting performance and compare post-operative racing performance with pre-operative data and case-matched controls. Methods: Retrospective case series. Methods: Thoroughbred racehorses that underwent PSBF repair (2008-2022) were included. Data retrieved included fracture type, limb, axiality, treatment, age, sex, suspensory ligament branch (SLB) injury, surgical date, date of racing return, and pre- and post-operative starts and places (1-3), which generated a performance index (PI) and PI per start (PI/S). Chi-squared assessed the effect of categorical variables (sex, limb, fracture type, axiality, SLB injury and pre-surgical racing experience) on racing outcome. Wilcoxon signed-rank test compared pre- and post-operative performance indices. Kruskal-Wallis and Mann-Whitney U tests assessed significance between categorical variables and numerical variables (age, recovery, number of starts (Nstarts), and performance indices). Binary logistical regression performed multivariable analysis. Change in PI and PI/S, and Nstarts were compared between matched controls and cases using Mann-Whitney U tests. Results: Overall, 86/168; 51.2% (confidence interval (CI): 43.5%-58.9%) horses raced post-operatively. Of the 113 horses that raced pre-operatively, 57 raced post-operatively (50.4%, CI: 41.8%-59.3%). Forelimb fracture cases (42.3%) were less likely to race post-operatively compared with hindlimb cases (65.6%, p = 0.003). In univariable analysis, horses that underwent surgical management of mid-body fractures (15.8%) were less likely to race compared with other fracture types (apical 56.1%, abaxial 60.5% and basal 25%, p = 0.001). Horses undergoing screw-fixation were less likely to race compared with fragment-removal (17.4% vs. 56.6%, p = 0.001). Axiality, pre-operative racing and SLB injury did not affect return-to-racing. No significance was observed for post-operative Nstarts, change in PI, change in PI/S or the return-to-racing proportion between cases and controls. Conclusions: The retrospective nature and drop-out rate limited post-operative analysis. Conclusions: Surgical management of apical and abaxial PSBFs via fragment removal is associated with improved post-operative outcomes compared with PSBFs necessitating internal fixation. Limb is a significant determining factor for return to racing. Post-operative racers have good longevity, although reduced PI/S compared with pre-operative performance.
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Publication Date: 2025-09-19 PubMed ID: 40974060DOI: 10.1111/evj.70102Google 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.

Research Overview

  • This study analyzed Thoroughbred racehorses who had surgery to repair fractures in their proximal sesamoid bones, a common cause of financial loss in racing.
  • The researchers investigated factors influencing horses’ ability to return to racing and their performance after surgery compared to before surgery and matched controls.

Background and Purpose

  • Proximal sesamoid bone fractures (PSBFs) occur frequently in racehorses and significantly impact the economics of racing due to loss of training and racing potential.
  • Previous research had not recently focused on updated outcomes or the factors influencing post-operative racing performance.
  • The objective was to provide an updated analysis of racing outcomes after surgical repair of PSBFs and identify variables affecting performance.
  • The study also compared post-operative outcomes with pre-operative performance data and with case-matched (similar) control horses that did not have these fractures.

Methods

  • Study design was a retrospective case series, reviewing records of Thoroughbred racehorses treated surgically for PSBFs from 2008 to 2022.
  • Data collected included:
    • Fracture characteristics: type (apical, abaxial, mid-body, basal), limb affected (forelimb or hindlimb), and axiality
    • Demographics: age and sex
    • Surgical details: treatment technique (screw fixation or fragment removal), presence of suspensory ligament branch (SLB) injury
    • Performance metrics: dates of surgery and return to racing, number of race starts before and after surgery, and finishing positions (1st to 3rd)
  • Performance was quantified by a performance index (PI) and PI per start (PI/S).
  • Statistical tests included:
    • Chi-square to assess categorical variables’ effect (sex, limb, fracture type, axiality, SLB injury, prior racing experience) on whether horses raced after surgery
    • Wilcoxon signed-rank test to compare pre- and post-operative performance indices
    • Kruskal-Wallis and Mann-Whitney U tests to evaluate relationships between numerical variables and categorical groups
    • Binary logistic regression for multivariable analysis
    • Mann-Whitney U tests to compare post-operative changes in PI, PI/S, and number of starts between surgical cases and matched controls

Results

  • Out of 168 horses, 86 (51.2%) returned to racing after surgery.
  • Among 113 horses that had raced before injury, 57 (50.4%) raced again after surgery.
  • Limb affected was significant: horses with forelimb fractures had a lower return-to-racing rate (42.3%) than those with hindlimb fractures (65.6%), a statistically significant difference.
  • Fracture type influenced outcomes:
    • Mid-body fractures had the lowest likelihood to race post-operatively (15.8%).
    • Apical (56.1%) and abaxial (60.5%) fracture types had higher return rates.
    • Basal fractures had an intermediate likelihood (25%).
  • Surgical technique influenced return to racing:
    • Horses treated with screw fixation returned less often to racing (17.4%) compared to those with fragment removal (56.6%).
  • Variables that did not significantly affect return to racing included axiality, prior racing experience, and the presence of suspensory ligament branch injury.
  • Comparison of post-operative performance with matched controls revealed:
    • No significant difference in number of starts, change in performance index, or PI per start.
    • Indicates similar longevity and performance potential after surgery in horses that returned to racing.

Conclusions and Implications

  • The study is limited by its retrospective design and the dropout rate (horses that did not return to racing), which restricted full analysis of post-operative performance.
  • Surgical management by fragment removal of certain fracture types (apical and abaxial) was associated with better outcomes compared to screw fixation needed for other fracture types.
  • The limb affected (forelimb vs. hindlimb) significantly influenced the chance of returning to race, with forelimb fractures having poorer prognosis.
  • Post-operative racers demonstrated good longevity—meaning they raced for a comparable number of starts—but their performance index per start was lower than prior to injury.
  • This suggests that while horses can return to race after PSBF surgical repair, some decrease in racing performance is expected.
  • The findings help inform veterinarians, trainers, and owners about prognosis factors influencing recovery and performance after PSBF surgery in Thoroughbreds.

Cite This Article

APA
Yeomans A, Cramp P, Carpenter R, Bladon B. (2025). Retrospective performance-indexed analysis of Thoroughbred racehorses undergoing surgical management of proximal sesamoid bone fractures. Equine Vet J. https://doi.org/10.1111/evj.70102

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English

Researcher Affiliations

Yeomans, A
  • Hambleton Equine Clinic, North Yorkshire, UK.
Cramp, P
  • Hambleton Equine Clinic, North Yorkshire, UK.
Carpenter, R
  • Equine Medical Center, Cypress, California, USA.
Bladon, B
  • Donnington Grove Veterinary Group, Newbury, UK.

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