Researchers Study Sesamoid Bone Shape Differences

Researchers found that none of the evaluated bones showed significant shape changes after training and racing.
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The training and racing of 2-year-old Thoroughbreds has always been a source of debate in the racing world due to concerns that exerting young skeletons might make horses more likely to injure themselves. But recent study results from Italian researchers suggest that at least one set of bones in Thoroughbreds might not impacted by training as juveniles: the sesamoids.

The researchers, led by Francesca Beccati, DVM, PhD, of the University of Perugia, looked at 27 2-year-old Thoroughbreds’ proximal sesamoid bones (PSB)—the two small bones that form the rear portion of the fetlock joints—studying the differences in bone height and width in the horses’ forelegs.

Beccati and colleagues measured the bone dimensions before and after the horses partook in one year of exercise and racing. Before the horses hit the track, researchers found a significant difference between the shape of the medial and lateral (inside and outside, respectively) proximal sesamoids, as well as differences between the bones in the right and left legs.

Specifically, the team found that the inside proximal sesamoids were significantly shorter and wider than the outside sesamoids in both legs, while the inside proximal sesamoid in the right leg was, on average, wider than that of the inside proximal sesamoid in the left leg. The differences were not significant enough to see under close examination with the naked eye, but were easily measured when the joints were radiographed (X rayed)

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Natalie Voss is a freelance writer and editor based in Kentucky. She received her bachelor’s degree in equine science from the University of Kentucky and has worked in public relations for equine businesses and organizations. She spends her spare time riding her Draft cross, Jitterbug.

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