Development of a 3D model of the equine distal forelimb and of a GRF shoe for noninvasive determination of in vivo tendon and ligament loads and strains.

This research article presents the development of a 3D model of a horse’s forelimb and a ground reaction force recording shoe (GRF-S). These tools non-invasively measure forces and strains in the tendons and ligaments of the horse during movement, with the aim of better understanding and preventing locomotion-related injuries.

Methods

• The researchers utilized a power press to recreate the forces experienced by a horse’s forelimb during different types of movement. The power press applied varying compression cycles from 500 to 6000 N to the equine distal forelimb models in different orientations.
• The bony segments of the forelimbs and the locations of tendons and ligaments were tracked with ultrasonic kinematic markers. These markers enabled a 3D reconstruction of the limb movements under the applied forces.
• The team also developed a specialized shoe, the GRF-S, that was equipped with four 3-axis force sensors. These sensors were placed between a support shoe and the actual shoe, enabling them to accurately record the ground reaction force (GRF) exerted over the hoof wall during movement.

Results

• The developed model and GRF-S were able to successfully validate the calculated and measured strains on the superficial digital flexor tendon. This tendon is key to a horse’s ability to move and run efficiently, making this validation a crucial success.
• The study was also able to assess the role of the proximal interphalangeal joint in the strain experienced by the straight and oblique sesamoidean ligaments. These ligaments play significant roles in the horse’s locomotion system.
• Reliable comparisons of the three components of GRF over the hoof wall on soft and hard ground surfaces were conducted. It was found that the standard deviation of the GRF norm was greater on hard ground at both the walk and trot gaits.

Conclusion

• Soft surfaces, such as sand and rubber, were found to reduce the GRF value, effectively helping to dissipate energy and reducing vibrations upon impact. This reveals that these surfaces are advantageous for horses, likely minimizing the risk of locomotion-related injuries.
• The researchers found that the stance phase was longer on soft sand ground at a comparable speed. This finding could provide useful insights for designing better shoes or training grounds for horses.
• The research suggests that the combined use of the model and the GRF-S shoe can be employed to analyze how different ground and shoe combinations can affect the horse’s comfort, propulsion efficiency, and recovery from lameness. This can provide valuable insight for preventing injuries and improving horse welfare.