Bending properties of cortical bone of the horse.

The research conducted deals with the properties and strength of the cortical bone, the outer layer of bone, in horses. The study focuses specifically on various locations of bone within the body, how these different quadrants compare in strength and elasticity, and how factors such as exercise, gender, and diet can influence these properties.

Research Methodology

• The study examined cortical bone samples from different areas (cranial, caudal, medial, and lateral quadrants) of the midshaft of the radius, femur, and metacarpus bones in 12 ponies aged 18 months.
• The bending properties of these samples were determined using a method of force application known as 4-point loading at a rate of 10 mm per minute.

Findings on Bending Properties

• The elastic modulus, a measure of a material’s ability to deform elastically when a load is applied to it, ranged between 16.2 and 20.2 GN/m2 for all the samples.
• The ultimate breaking strength of the samples, which signifies the maximum amount of tensile stress a material can withstand without breaking, varied between 204 and 255 MN/m2.
• A key observation was that there was more variation in these properties between bone quadrants than between different types of bone.
• In terms of performance by quadrant, samples from the cranial and medial quadrants of both the femur and radius were stiffer and had greater ultimate breaking strength than the caudal or lateral samples.
• The radial bone samples in general deformed more and absorbed more energy before reaching their maximum load as compared to the femoral bone samples.

Correlation with Specific Gravity and Influencing Factors

• The researchers established a strong correlation between the elastic modulus and the ultimate breaking strength of the radius within any quadrant to specific gravity. Specific gravity refers to the density of a substance compared to the density of a reference substance.
• However, at any specific gravity, bones from the caudal and lateral quadrants were not as strong as those from cranial and medial quadrants.
• The study also concluded that different external factors could influence the sturdiness and elastic modulus of the bone.
• It was observed that samples taken from ponies that had undergone exercise, male ponies, or those fed with specific diets containing 0.7% Calcium and 0.6% Phosphorus or 2.7% Calcium and 1.1% Phosphorus seemed to be stiffer and have a greater breaking strength. This was in contrast to samples taken from unexercised ponies, females, or those fed with diets containing 0.7% Calcium and 1.4% Phosphorus.

The findings of this study provide understanding on how structural properties of bone may vary between different locations and the possible factors that can influence these properties, having potential implications in horse health, specifically in relation to bone health and strength.