Fractures--a preventable hazard of racing thoroughbreds?
Authors: Riggs C M
Journal: Veterinary journal (London, England : 1997)
Summary
# Editorial Summary: Fractures as a Preventable Hazard in Racing Thoroughbreds Riggs's 2002 review examines the biomechanical and biological mechanisms underlying the high incidence of stress fractures in Thoroughbred racehorses, particularly those occurring without obvious traumatic cause. The analysis synthesises evidence from bone adaptation studies showing that whilst the third metacarpal bone does modify its geometric properties in response to training—changes that ultimately reduce strain—this adaptive process takes time, and premature intense exercise before remodelling is complete creates a critical window of vulnerability. Key to understanding fracture risk is the interplay between microdamage accumulation (fatigue of bone) and the biological remodelling process itself; horses returned to work before bone repair is complete face substantially elevated risk of catastrophic failure despite appearing sound. The morphological consistency of these injuries and their frequent association with pre-existing pathology such as periosteal new bone formation suggests stress fractures follow predictable mechanical patterns rather than representing random accidents. For practitioners, this framework implies that training periodisation and graduated work schedules are not merely performance tools but essential preventive measures, with the implication that enforced rest periods during the remodelling phase may be more critical to fracture prevention than previously recognised in racing practice.
Read the full abstract on PubMed
Practical Takeaways
- •Structure progressive training schedules to allow adequate time for bone adaptation and remodelling before increasing intensity, particularly in young Thoroughbreds
- •Monitor for pre-existing bone pathology (new bone formation, intracortical remodelling) as indicators of increased stress fracture risk
- •Allow complete recovery periods during training programmes to minimize catastrophic fracture risk in racehorses
Key Findings
- •Stress fractures in Thoroughbreds frequently occur without specific trauma and show consistent morphology with pre-existing pathology including periosteal and endosteal new bone formation
- •Bone adapts to training through geometric property modifications in the third metacarpal, reducing bone strains when adaptation is complete
- •Intense training before adaptive bone response completion increases fatigue microdamage risk and catastrophic stress fracture development
- •Bone remodelling, while a repair mechanism, also contributes to stress fracture pathogenesis when horses are exercised before repair completion