In vitro transmission and attenuation of impact vibrations in the distal forelimb.

This research aimed to develop an in vitro model to measure the attenuation of impact vibrations transmitted through the lower forelimb of horses and assess the influence of horseshoeing on this attenuation. It found that roughly two-thirds of the damping occurs at the hoof wall, with shoeing slightly increasing the amplitude at the hoof wall, although this difference vanishes further up the limb.

Research Methodology

• The research began by setting up an in vitro model. The lower limbs of 13 horses were fitted with custom-made hollow bone screws. Tri-axial accelerometers were mounted on these screws to record vibrations.
• Next, an impact on the hooves was simulated by dropping a weight onto the steel plate on which the hoof rested. The shock waves from the impact were quantified at the hoof wall, the distal, middle, and proximal phalanx, and at the metacarpal bone.

Shoeing Variances

• To understand the mitigating effects of horseshoeing, measurements were made with unshod hooves, normal flat shoe shod hooves, and hooves shod with equisoft pad having a silicone filling between the hoof and pad.

Results and Conclusions

• The in vitro model found that about 67% of the damping of vibrations occurred at the interface between the hoof wall and the distal phalanx when the hoof suffered an impact.
• The vibration dampening at the distal and proximal interphalangeal joints was considerably less at only 6%, while at the metacarpophalangeal joint, 9% of the amplitude from the initial impact at the hoof wall was absorbed, leaving about 13% of the initial amplitude detectable at the metacarpus
• The measurements revealed that compared to unshod hooves, the vibration amplitude at the hoof wall is 15% higher in shod hooves. However, no differences were observed between different types of shoes.
• At the first phalanx and metacarpus level, the difference in impact vibrations between shod and unshod hooves diminished, indicating that while shoeing could influence the amplitude of impact vibrations at the hoof wall, its effect further up the leg, at the metacarpophalangeal joint, is minimal.

Model Validation

• The researchers validated the in vitro model by performing the same measurements on one horse both in vivo and in vitro after death and found consistent results.