Determination of mechanical loading components of the equine metacarpus from measurements of strain during walking.

The research study revolves around understanding the mechanical loads exerted on the metacarpus (a part of the forelimb) of horses during walking. This aims to help develop hypotheses related to the causes of distal limb injuries and validating mathematical models of the limb.

Objective and Methods

• The primary objective of this study was to explore the forces and moments experienced by the metacarpus of a horse in real-time during walking. It also aimed to evaluate the impact of some simplifying assumptions used in the analysis.
• Researchers attached eight strain gauges to a horse’s left metacarpus. These gauges recorded the strains when the horse was in motion, walking.
• Two different models – one based on the mechanical theory associated with beams and shafts, and one based on finite element analysis (FEA) – were used to determine the external loads applied at the endings of the bone.

Results

• Analysis of the data revealed five orthogonal force and moment components. In addition to this, two orthogonal bending moments were calculated around the mid-shaft of the metacarpus.
• The axial force was identified as the major component of load and exhibited a bi-modal pattern during the stance phase of the stride, i.e., when the horse’s foot was grounded during walking.
• The shaft model of the bone, despite its simplifying assumptions, showed impressive agreement with the FEA model.

Conclusions

• The research pointed out a three-dimensional loading scenario in the metacarpus, in which the axial force appeared to be the primary component.
• The results of the study offer an opportunity to validate mathematical or computer models of the limb, as they provide real-life, quantifiable data on the forces experienced by bones during movement.
• These findings may also contribute to the creation of hypotheses regarding the causes of injuries to the distal limb. This can further aid in developing preventive measures or treatment strategies for such injuries in animals.