Bone strain in the equine tibia: an in vivo strain gauge analysis.

The research article details a study examining the strain experienced by the bones of ponies as they walk. The researchers notably used physical gauges to measure the tension and compression in the tibias of the animals, and found that the condition of the cranial tibial muscle had little impact on this strain.

Methodology

• The researcher used rosette strain gauges, which were bonded to the cranial (front), caudal (back) and medial (middle) surfaces of the tibia in the middiaphyseal region, or middle of the shaft, of six adult ponies.
• These gauges were used to measure the strain on the bone while the ponies were walking.

Findings

• They discovered that when the ponies walked, the cranial side of the tibia mainly underwent tension, while the caudal side predominantly experienced compression.
• The compression strain on the caudal side was 1.5 times greater than the tension strain on the cranial side.
• Interestingly, none of the principal strains were aligned along the length of the bone, but instead veered off to the side.
• More strangely, on the medial surface, the strain deviated around a 40-degree angle from the length of the bone to the caudal side.
• The findings from these strain patterns suggest that during loading of the tibia, torsion (or twisting) occurs alongside craniocaudal bending (bending along the length of the bone).

Impact of Cranial Tibial Muscle

• The researchers measured the strain patterns on the tibia both before and after surgically transecting, or cutting across, the cranial tibial muscle to observe any changes.
• There were no significant changes in the strain pattern following this interference, leading the researchers to conclude that the cranial tibial muscle does not significantly contribute to reducing strain in the tibial cortex, or outer part of the tibia.