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veterinary
2025
Cohort Study

The effect of heel elevation on the stiffness gradient index of the digital flexor tendons in the equine forelimb of clinically normal horses.

Authors: Shaw Kelly A, Brounts Sabrina H

Journal: Frontiers in veterinary science

Summary

# Editorial Summary: Heel Elevation and Digital Flexor Tendon Stiffness Acoustoelastography (AEG) offers farriers and veterinarians a non-invasive means of measuring how digital flexor tendons respond to different heel angles, a finding that Shaw and Brounts have now quantified in 15 clinically normal horses using incremental heel elevations of 0, 4, and 8 degrees. By measuring stiffness gradient index (SGI) at three metacarpal sites on both the superficial and deep digital flexor tendons under loaded and unloaded conditions, the researchers found that heel elevation significantly altered tendon stiffness, with the most consistent changes occurring in the mid-metacarpus and a tendency towards decreased stiffness as heel angle increased. Crucially, loading the contralateral limb during imaging—which simulates weight-bearing—substantially reduced measurement variability and demonstrated that SGI values differed markedly between loaded and unloaded states, highlighting the importance of functional assessment in standing horses. These findings provide practitioners with objective data to correlate specific heel angles with measurable changes in tendon mechanics, enabling more evidence-based decisions when adjusting shoeing angles for individual conformation and potentially preventing or managing flexor tendon injuries through targeted farriery. The practical value lies not merely in understanding that heel elevation changes tendon stiffness, but in having a reproducible imaging protocol that quantifies these changes in the living, weight-bearing horse—information previously available only through cadaveric or static analysis.

Read the full abstract on PubMed

Practical Takeaways

  • Heel elevation measurably reduces stiffness in digital flexor tendons, particularly in the mid-metacarpal region—this supports targeted therapeutic farriery decisions based on individual conformation.
  • Loading the limb during imaging produces more reliable measurements of tendon strain, suggesting the relevance of assessing tendons under weight-bearing conditions rather than statically.
  • Acoustoelastography offers farriers and veterinarians a non-invasive, in-hand method to evaluate how heel elevation affects tendon biomechanics in standing horses, enabling evidence-based shoeing adjustments.

Key Findings

  • Stiffness gradient index (SGI) of both SDFT and DDFT differed significantly between loaded and unloaded tendons, with reduced variability in loaded conditions.
  • Incremental heel elevation from 0 to 8 degrees produced the greatest and most consistent effect on SGI in the mid-metacarpal region of both flexor tendons.
  • SGI values decreased with increased heel elevation angles from 0 to 8 degrees in both superficial and deep digital flexor tendons.
  • Acoustoelastography can be used effectively in standing horses to quantify tendon strain in relation to distal limb conformation and heel elevation.

Conditions Studied

clinically normal horsesdigital flexor tendon biomechanicsheel elevation effects