Catastrophic biaxial proximal sesamoid bone fractures in UK Thoroughbred races (1999-2004): horse characteristics and racing history.
Authors: Kristoffersen M, Parkin T D H, Singer E R
Journal: Equine veterinary journal
Summary
# Catastrophic Biaxial Proximal Sesamoid Bone Fractures in UK Thoroughbred Racing Between 1999 and 2004, researchers prospectively collected distal limbs from all UK racehorses that sustained catastrophic fractures during racing, identifying 31 cases of biaxial proximal sesamoid bone fractures (PSBF) through post-mortem examination and correlating these with detailed racing histories and horse demographics. The overall incidence was 0.63 per 10,000 race starts, but this masked substantial variation by surface type: flat racing on all-weather surfaces carried a dramatically elevated risk of 1.63 per 10,000 starts—approximately 4.4 times higher than turf flat racing—suggesting surface characteristics play a critical aetiological role in this catastrophic injury. Affected horses averaged 5.6 years old with approximately 28 race starts at the time of fracture, indicating these injuries typically occur in experienced campaigners rather than horses early in their racing careers. The strong association with all-weather surfaces warrants investigation into specific surface properties and their biomechanical effects on the proximal sesamoid bones, whilst the relatively low overall incidence highlights the challenge in identifying underlying predisposing factors without substantially larger datasets accumulated over extended periods. For practitioners involved in racing soundness assessment and injury prevention, this finding emphasises the need for heightened vigilance in horses with significant racing experience competing on artificial surfaces, though mechanistic understanding remains limited.
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Practical Takeaways
- •All-weather track surfaces present significantly higher risk for catastrophic sesamoid fractures—consider surface type when advising on racing strategy or training venues
- •Target preventive monitoring and conditioning programmes toward horses with 20+ career starts on all-weather surfaces, as these appear to be the highest-risk population
- •Early-career fractures are rare; focus investigation and risk mitigation on horses with established racing histories rather than young stock entering training
Key Findings
- •Incidence of PSBF was 0.63 per 10,000 starts across all UK racing types (31/494,744 starts over 1999-2004)
- •Flat racing on all-weather surfaces carried 4.4-fold increased risk compared to turf flat racing (1.63 vs 0.37 per 10,000 starts)
- •Affected horses averaged 5.6 years old with mean 28 career starts, indicating fractures occur in experienced horses rather than early in racing careers
- •Few PSBF occurred within horses' first season of racing, suggesting cumulative stress or pathology development is involved