The forelimb in walking horses: 1. Kinematics and ground reaction forces.

The study investigates the forelimb movements and ground reaction forces of a horse during walking, concluding that the rotation of different parts of the limb results in elevation and lowering of the limb for ground contact and that the movements of the forelimb vary throughout different phases of a stride.

Objective of the Study

• The goal of this research was to analyse the forelimb movements and ground reaction forces (GRFs) of a walking horse, with the eventual aim of using this normative data to detect changes in kinematics and GRFs linked to specific lamenesses in horses.

Methodology of the Study

• The researchers used video (60Hz) and force (2000Hz) data gathered from five horses to evaluate the walking pattern of the horses.
• The team focused on eight strides for each horse (four left and four right) to gain a comprehensive understanding of the horse’s locomotion.

Key Findings and Conclusions

• The study found that the rotation of the brachium (essentially the “arm” part of the horse, from shoulder to elbow) controls the protraction (forward) and retraction (backward) movements of the limb.
• The scapula (shoulder blade) and antebrachium (forearm, elbow to knee equivalent in human anatomy) rotations increase the distance of the limb from the ground during breakover and early swing, and later lower it for ground contact.
• The coffin joint, which corresponds roughly to a human’s knuckle joint at the base of the fingers, flexes most when the opposing forelimb is at the breakover phase of its stride, which is when the braking force is the strongest.
• The study also points out that the changeover from braking to propulsion force in the stride happens later than when the metacarpus (similar to the human hand from wrist to knuckles) is vertical, coinciding with the maximal extension of the fetlock joint (similar to the human finger joints).
• In the swing phase, the horse’s joints exhibit a single flexion cycle that peaked sequentially at the carpus (wrist equivalent), fetlock, elbow and coffin joints. The coffin and shoulder joints began to extend towards the end of the swing phase and continued to do so through ground contact and early stance.
• This study’s results offer valuable information about the natural mechanics of a horse’s walk and may be used in future efforts to identify lameness within horses based on changes in their walking patterns.