Morphometrical study of bony elements of the forelimb fetlock joints in horses.

This research studied the dimensions of different bones in the horse’s forelimb fetlock joint, intending to understand the normal variation in bone size and shape across different horse breeds. Such insights can be vital in understanding the susceptibility of these bones to breakage under different loads or stresses.

Objective and Methodology

• The primary objective of this study was to identify the typical size and shape variations of the bones in the forelimb fetlock joints of horses. This knowledge is crucial because fractures in these bones are commonly reported, with some studies suggesting that these fractures could be related to mechanical stress on these bones. To gain understanding in this area, we need to first understand the normal range for the size and shape of these bones in horses, which this study aimed to fill.
• The research was conducted on right and left metacarpal, proximal phalangeal and proximal sesamoid bones collected from different types of horses – 10 Thoroughbreds (TB), five Standardbreds (SB), and eight Ponies (P). These horses were euthanized due to non-orthopaedic reasons, ensuring that the bones studied were generally typical and free from orthopaedic diseases.
• After collection, these bones were boiled, cleaned, and dried. Their dimensions were measured using a custom-built apparatus, calliper, and plastic tape.

Results and Findings

• The researchers found variations in the dimensions of specific bones. For example, in all types of horses, the medial condyles of the Mc3 bones were wider and deeper than the lateral condyles. The length to the lateral condyle was also found to be greater than the length to the medial condyle.
• The lengths of the lateral sides of the Mc3 and P1 bones were greater than the lengths of the medial sides in both forelimbs across all horse types studied.
• The study also discovered that the lateral sesamoids were similar to, or larger than, the medial sesamoids in all dimensions.
• In conclusion, this research found that there are indeed morphometrical variations in the bony elements of the equine fetlock joints across all the horse groups investigated.

Implications of Study

• The findings of this study contribute to the understanding of the normal range of dimensions of the bony elements of the equine fetlock joint in different types of horses.
• This knowledge can be used in future research to examine the relationships between fractures and the mechanical loading of these bones. It may potentially help in refining training, conditioning, and treatment protocols for equine athletes, enhancing their performance and welfare.