The forelimb in walking horses: 2. Net joint moments and joint powers.

This research sought to evaluate the net joint moments and joint powers in the forelimbs of horses during walking. The team used videographic and force data, combined with morphometric information, to understand that predominantly, the elbow joint generates energy while the shoulder and coffin joints act as energy dampers. This information can give insights on how horses adapt to various lameness conditions.

Research Methodology

• Data for this study was gathered from videographic and force measures, which were coupled with morphometric information about horses.
• This collected information was analyzed using an inverse dynamics approach to measure the net joint moments and joint powers in the equine forelimb during the walk.

Major Findings

• The primary joint moment during the stance phase was found on the palmar aspect of all forelimb joints except the shoulder. Here, the peak moment was considerably higher than at any other joint.
• The forelimb as a whole showed net energy absorption in both stance and swing phases.
• The elbow joint was the only one that showed net generation of energy. It was used to keep the limb extended in early stance as the horse’s body vaults over the limb and to control the protraction and retraction of the limb during the swing phase.
• The carpus joint aligned the limb into a supportive strut. It did not play a significant role in absorbing or generating energy. However, a small surge of positive work on the flexor aspect at the start of breakover indicated that the carpus contributed to initiating breakover during walking.
• The fetlock worked as an elastic mechanism to store and release strain energy during stance. Alternatively, the coffin joint functioned as an energy damper throughout most of the stance. There was a small burst of energy generation on the flexor aspect when the joint flexed during breakover.
• The magnitude of peak joint power during the swing phase was observed to decrease in a proximal to distal sequence.

Conclusions

• Based on the results, researchers concluded that the main site of energy generation is the elbow joint.
• The shoulder and coffin joints act mostly as energy dampers during the stance.
• The distal joints had very low joint powers, suggesting that they are driven by inertial forces during the swing phase.
• The study’s findings are essential in describing how horses adjust to different lameness conditions by redistributing the functions of energy generation and absorption between joints.