Surface strains around the midshaft of the third metacarpal bone during turning.

The research study focuses on how bone strains occur on the third metacarpal (McIII) bone of horses during turning movements and the implications these strains have on exercise design and injury prevention. The study found that these strains change in different areas of the bone depending on whether the McIII is on the inside or outside of the turning circle.

Objective and Methodology

• The main aim of the research was to analyze whether the compressive strains increase on the lateral surface of the inside McIII and on the medial surface of the outside McIII during a turn.
• Two Thoroughbred geldings were involved in the study, and their movements were analyzed using rosette strain gauges on the dorsal, medial, and lateral surfaces of the midshaft of their left McIII.
• The horses were observed during turning movements at walking speeds on a bitumen surface.

Results

• The compression peaks were larger on the medial surface of the outside limb while the tension peaks were more pronounced on the inside limb, especially during tighter turns.
• On the lateral surface, both compression and tension peaks were larger on the inside limb. The largest recorded strain was a compression of -1400 microstrains.
• Dorsal compression strains were more noticeable on the outside limb and on a larger circle. Tensile strains were similar in various directions, but they increased on a larger circle.

Conclusions

• The study confirmed that during a turn, compressive strains increased on the lateral surface of the inside McIII and the medial surface of the outside McIII.
• Results suggest that slow-speed turning exercises may be sufficient to maintain bone mechanical characteristics in the inside limb lateral McIII cortex.
• However, more research is required to validate the findings, especially to understand how faster gaits or tighter turns may affect the level of strain on the medial and lateral McIII cortex and potentially lead to bone remodeling.