Can quantitative computed tomography detect bone morphological changes associated with catastrophic proximal sesamoid bone fracture in Thoroughbred racehorses?
Authors: Cresswell E N, McDonough S P, Palmer S E, Hernandez C J, Reesink H L
Journal: Equine veterinary journal
Summary
# Editorial Summary: Proximal Sesamoid Bone Morphology and Fracture Risk in Thoroughbreds Proximal sesamoid bone fractures remain the leading cause of catastrophic musculoskeletal injury in racing Thoroughbreds, yet identifying which horses are at heightened risk remains challenging. Cresswell and colleagues used high-resolution micro-CT imaging to compare proximal sesamoid bone morphology from 16 Thoroughbreds (eight with fracture history, eight controls), measuring bone density, architecture and geometric traits across 62 sesamoid bones total. Fracture-prone horses demonstrated significantly greater bone volume fraction (90.39% versus 87.20%), increased bone width, thicker trabeculae, and altered trabecular orientation compared to controls—counterintuitively suggesting that denser bone was associated with fracture risk. A predictive model combining bone volume fraction and width achieved 93.8% accuracy in distinguishing fracture from control horses, indicating these morphological traits could serve as reliable biomarkers. Whilst current clinical CT cannot yet match the imaging resolution used in this cadaver study, the authors propose that quantitative CT using standard clinical settings could feasibly measure bone density and width in live horses, potentially enabling pre-emptive screening to identify high-risk individuals before catastrophic injury occurs.
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Practical Takeaways
- •Higher bone density in proximal sesamoid bones may paradoxically increase fracture risk rather than protect against it, challenging conventional assumptions about bone strength
- •As CT technology improves, pre-race screening using quantitative imaging of sesamoid morphology could identify high-risk racehorses and inform training/racing decisions to reduce catastrophic injuries
- •Current findings are limited to cadaver specimens; practitioners cannot yet use clinical CT for fracture risk assessment but should anticipate this tool becoming available
Key Findings
- •Bone volume fraction was significantly greater in fracture horses (90.39%) compared to controls (87.20%, P<0.0001)
- •A combined CT model using bone volume fraction and width achieved 0.938 AUC for identifying fracture-prone horses with high accuracy
- •Bone width, trabecular thickness, and degree of anisotropy were significantly different between fracture and control groups
- •Quantitative CT could potentially detect fracture risk morphological traits, though in vivo clinical resolution is not yet attainable