Body centre of mass movement in the lame horse.

The study investigates how lameness in horses affects the movement and position of the body center of mass (BCM), using a method of tracking movement across multiple body segments. The results suggest that lameness results in only minor shifts in BCM position, but significantly changes how the BCM moves, in ways that may matter for managing equine lameness.

Research Purpose and Methodology

• The aim of the study was to examine changes in the position and three-dimensional movement of a horse’s BCM when they suffer from lameness in their front limbs. The researchers hypothesized that these changes could be crucial in managing the lameness condition in horses.
• A high-speed video recording system was used to capture the kinematics of 30 markers representing 20 body segments across 12 horses as they trotted on a treadmill. The horses trotted at a speed of 3.9 metres per second.
• The lameness in the horses was induced for the purpose of the study, by applying pressure-evoked pain on the hoof sole. This transient lameness model generated two degrees of forelimb lameness.
• Three-dimensional segmental centres of mass, along with the BCM, were calculated based on segmental inertial data from a previous study by Buchner et al. (1997).

Key Findings

• Vertically, the BCM’s displacement amplitude reduced by 34% during the stance phase of the lame limb, whilst it increased by 9% during the stance phase of the healthy forelimb.
• In the sagittal plane, the BCM moved 9mm backwards during the stance phase of the lame forelimb during midstance.
• Transversely, a minor but significant shift of the BCM was noted to the side of the healthy forelimb.
• Movement changes were also noted both vertically and sagittally in the head/neck segment; however, these changes were small and did not greatly affect the BCM’s position.
• The findings also revealed a similarity between patterns of BCM movement and trunk movement, with only small changes in BCM position due to lameness.

Implications and Conclusion

• The finding suggests that, contrary to the original hypothesis, the sagittal position of the BCM seems to be of minimal significance in managing lameness.
• In contrast, the research provides strong evidence that the dynamic influences of altered vertical BCM movement and the moment caused by typical head and neck movements are much more significant.
• In conclusion, while lameness in horses causes some adaptation in the BCM’s position, the more substantial changes are those that occur in the way the BCM moves. This has significant implications on how lameness is managed, emphasizing the importance of taking BCM movement into account.