Finite element analysis of stress in the equine proximal phalanx.
Authors: O'Hare L M S, Cox P G, Jeffery N, Singer E R
Journal: Equine veterinary journal
Summary
# Editorial Summary: Finite Element Analysis of Stress in the Equine Proximal Phalanx O'Hare and colleagues used micro-computed tomography to create a three-dimensional digital model of the equine first phalanx (P1), then applied finite element analysis to simulate the bone's mechanical behaviour during stance, walk, trot and gallop. By applying literature-derived force values and material properties to this reconstructed model, they mapped stress distribution across P1 under progressively higher loading conditions, examining both scenarios where the sagittal groove bore load and where it remained unloaded. Gallop simulation revealed substantially elevated stress concentration along the sagittal groove and on the palmar surface immediately distal to it—a pattern consistent with clinical fracture location—whilst an unexpected low-stress zone emerged on the dorsal aspect of P1, more pronounced in the unloaded groove model. The minimal difference in stress patterns between loaded and unloaded groove models suggests the groove's structural geometry, rather than its functional load-bearing role, may be the critical factor in its biomechanical vulnerability. These findings provide computational evidence supporting long-standing clinical observations that P1 sagittal groove fractures are the most common type, and with further refinement to more accurately replicate in vivo loading conditions, such models could help predict injury risk and inform management strategies for high-impact disciplines.
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Practical Takeaways
- •High-speed work (gallop) creates substantially greater stress on the P1, particularly at the sagittal groove—the most common fracture site—suggesting conditioning and training intensity should be carefully managed to reduce fracture risk.
- •The study validates that P1 fractures are biomechanically predictable based on loading patterns, which may inform rehabilitation protocols and return-to-work timelines following injury.
- •Further refinement of this model could eventually guide preventative farriery and hoof management strategies by identifying how hoof trim and shoeing affect internal bone stress distribution.
Key Findings
- •Finite element model of equine proximal phalanx (P1) successfully replicated clinical fracture patterns with highest stress loads at the sagittal groove during gallop compared to stance.
- •Gallop forces produced significantly higher stress levels along the sagittal groove and palmar surface distal to the groove compared to stance, with minimal difference whether the sagittal groove was loaded or unloaded in the model.
- •The dorsal aspect of P1 demonstrated a localized area of lower stress compared to surrounding dorsal surface, particularly apparent when sagittal groove was not loaded in the model.
- •Simulated stress distribution patterns correlated with the most common clinical site of P1 fractures in horses, validating the finite element model's biomechanical accuracy.