Size and geometry of apical sesamoid fracture fragments as a determinant of prognosis in Thoroughbred racehorses.
Authors: Kamm J L, Bramlage L R, Schnabel L V, Ruggles A J, Embertson R M, Hopper S A
Journal: Equine veterinary journal
Summary
# Editorial Summary: Apical Sesamoid Fracture Prognosis in Racehorses When faced with apical proximal sesamoid bone (PSB) fractures in young Thoroughbreds, clinicians have traditionally used fragment size and geometry as prognostic indicators—yet evidence supporting this approach has been limited. This 2011 study examined 110 young horses and 56 training racehorses undergoing surgical removal of apical PSB fractures, measuring fracture dimensions radiographically and correlating these measurements with post-operative racing performance (average earnings per start and total starts). Whilst forelimb medial sesamoids in untrained racehorses did show significantly more transverse fracture patterns than other sesamoid locations, this geometric difference—and indeed all variations in fragment size and configuration—failed to predict post-operative outcomes. The practical implication is reassuring: surgical management decisions need not be influenced by whether a fracture is large or small, or by its orientation; prognosis appears independent of these radiographic variables, suggesting that fragment removal itself may be the primary determinant of success rather than the biomechanical characteristics of the injury pattern. This finding refines clinical decision-making by redirecting focus from fracture morphology towards surgical technique and post-operative management as the critical factors influencing return-to-racing soundness.
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Practical Takeaways
- •Fragment size and shape cannot be used to predict prognosis in horses with apical sesamoid fractures—do not use radiographic measurements to counsel owners on expected racing outcomes
- •Treatment decisions for apical sesamoid fractures should not be based on fracture geometry, as larger fractures do not result in worse performance outcomes
- •Forelimb medial sesamoid fractures tend to be more transverse in young horses, but this anatomical difference does not influence prognosis
Key Findings
- •Forelimb medial sesamoids in untrained racehorses had significantly larger abaxial to axial ratios (more transverse fractures) compared to all other sesamoids (P = 0.03)
- •No significant differences in fracture size were found between other anatomical locations of PSBs
- •Fracture size and geometry showed no relationship with average earnings per start (AEPS) or total postoperative starts
- •Horses undergoing surgery for larger apical PSB fractures had equivalent outcomes to those with smaller fractures