Relationship of foot conformation and force applied to the navicular bone of sound horses at the trot.
Authors: Eliashar, McGuigan, Wilson
Journal: Equine veterinary journal
Summary
# Editorial Summary: Foot Conformation and Navicular Loading in Sound Horses Whilst collapsed heels have long been suspected of predisposing horses to navicular disease through altered biomechanics, direct evidence linking specific hoof conformational parameters to the actual forces transmitted through the navicular bone has been lacking. Eliashar and colleagues used 3D motion analysis and force plate data collected from 31 working Irish Draught crosses during trotting, correlating lateromedial radiographic measurements of foot conformation with compressive forces on the navicular bone at key points throughout stance phase. Forces on the navicular bone were significantly negatively correlated with both the distal phalanx angle to ground and the ratio of heel to toe height, but—counterintuitively—heel collapse per se (measured as the change in heel angle relative to toe angle) showed no significant correlation with these forces. The practical implication is that farriers and veterinarians should prioritise assessment of absolute heel and toe height ratios and distal phalanx angle when evaluating conformation, rather than focusing on heel-toe parallelism; these parameters have measurable biomechanical consequences that may be clinically significant for navicular health, even in currently sound horses.
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Practical Takeaways
- •When assessing hoof conformation, prioritize measuring the distal phalanx angle and heel-to-toe height ratio rather than relying on visual heel-toe parallelism, as these correlate directly with forces on the navicular bone
- •Farriers should aim to maintain adequate heel height relative to toe length, as this reduces compressive forces on the navicular bone and may help prevent or manage navicular disease
- •Heel collapse defined by heel-toe angle parallelism alone is insufficient for predicting navicular disease risk; a more detailed biomechanical assessment is warranted in cases of concern
Key Findings
- •Force on the navicular bone was negatively correlated with distal phalanx angle to ground (P<0.05) and heel-to-toe height ratio (P<0.05)
- •Heel collapse as measured by heel angle change relative to toe angle showed no significant correlation with navicular bone force parameters
- •Distal phalanx angle and heel-to-toe height ratio are more accurate predictors of navicular forces than traditional heel collapse measurements
- •Forces on the foot vary significantly across stance phase (15%, 50%, and 86% of stance) with strong biomechanical relationships to specific hoof conformation parameters